Abstract

The influence of high-temperature postgrowth annealing (PGA) under NH3/H2, NH3/N2 ambience on the morphologies and nitridation degree of GaN/AlN QDs grown via droplet epitaxy is investigated. The results show that the size and density of GaN QDs changes with different ambiences and the NH3/N2 ambience is demonstrated as a necessary condition for maintaining optimal QD morphology by suppressing the migration and evaporation of Ga atoms and preventing the GaN decomposition. Moreover, the PGA process can effectively enhance the nitridation and crystallization of GaN QDs and the photoluminescence performance has been effectively improved after annealed under NH3/N2 ambience.

© 2015 Optical Society of America

1. Introduction

Self-assembled GaN quantum dot (QDs) have been the recent focus owing to the promising applications for different devices such as ultraviolet light-emitting-diodes (LEDs) [1, 2], single-photon sources [3], single-electron transistors [4], memory devices [5], and infrared photodetectors [6]. The fabrication of self-assembly GaN QDs has been extensively investigated, and the most frequently used approach is self-assembly process in Stranski-Krastanov (SK) growth modes which requires sufficient lattice mismatch and usually results in a 2D wetting layer [7, 8]. An alternative self-assembly growth approach is Ga droplet epitaxy which is based on vapor-liquid-solid (VLS) mechanism [9]. This technique offers distinct advantages in size and density manipulation which can be finely tailored by tuning the amount of deposited Ga and substrate temperature [10]. Although some researchers have reported the successful fabrication of GaN QDs using Ga droplet epitaxy, only few of them studied the optical performances of the obtained GaN QDs at room temperature because this technique brings serious birth defects due to the incomplete nitridation of Ga droplet at low temperature, leading to the poor optical performances of the obtained GaN QDs [11, 12]. Therefore, it is important to investigate the post-growth annealing (PGA) treatments to enhance the nitridation of Ga droplet. However, most PGA studies concerning GaN QDs are about the SK grown QDs [1315]. In this letter, we have investigated the influence of high-temperature PGA under NH3/H2, NH3/N2 ambience on the morphologies and nitridation of GaN QDs grown via Ga droplet epitaxy. Strong PL emissions of GaN QDs after PGA are observed at room temperature.

2. Experiment

The GaN QDs were grown on c-plane sapphire substrates by metal-organic chemical vapor deposition (MOCVD) under the reactor pressure of 40 torr. Triethylgallium (TEG), trimethylaluminum (TMAl) and ammonia (NH3) were used as precursors for Ga, Al and N sources with H2 as carrier gas. Prior to GaN deposition, a 300 nm thick AlN consisting of ~20 nm thick AlN nucleation layer grown at 670 °C and ~280 nm thick AlN epilayer grown at 1050 °C was first deposited, the details of which can be found elsewhere [16]. After that, NH3 were purged for 2 minutes. Then Ga droplets were formed on the AlN templates by introducing the TEG into the reactor for 12 seconds in the absence of NH3 flow at 600 °C, and the flow of TEG is 7.5 μmol/min. Subsequently, the initial nitridation of Ga droplet was carried out by importing the NH3 flow of 2000 sccm (standard cubic centimeters per minute) for 12 seconds at the same temperature. Afterwards, 12-second PGA at different elevated temperatures was performed in two different ambient, NH3/H2 and NH3/N2, in which the NH3 flow rate was kept constant of 2000 sccm. For comparison, the ramp time for these samples are all 3 min and 2000 sccm NH3 is supplied during this time. What’s more, 2000 sccm NH3 is supplied during cooling down to prevent the GaN QDs from decomposing.

3. Results and discussion

Figure 1(a) exhibits the morphologies of as-grown GaN dots or Ga metallic dots, which was directly cooled down after 12 seconds introduction of NH3. The size of the dots is quite uniform. Most dots have an average diameter of 40 nm and height of 3.5 nm. The total density of dots is 8.0 × 1010 cm−2. Figure 2 shows the morphologies of GaN QDs annealed at elevated temperatures from 700 °C to 900 °C under NH3/H2 [(a)-(d)] and NH3/N2 [(e)-(h)] ambience and the quantitative statistics of morphologies are listed in Table 1 . For the samples annealed under NH3/H2 ambience, the following behaviors are observed. After the QDs were annealed at 700 °C, some larger QDs with the average diameter of 60 nm and height of 4 nm are observed as shown in Fig. 2(a), and the density is reduced to 2.2 × 1010 cm−2. With the increase of the annealing temperature to 750 °C, the QDs density is further reduced (4.0 × 109 cm−2) and even larger QDs present with the average diameter of 80 nm and height of 5 nm. This is the typical Oswald ripening process [17], during which larger islands grow at the expense of the smaller ones. However, as the temperature increased to 800 °C and 850 °C, GaN QDs disappeared, leaving a flat surface. This is expected due to the decomposition of GaN at high temperature with the presence of H2 [18, 19].

 figure: Fig. 1

Fig. 1 AFM images of GaN dots or Ga metallic dots without annealing in scan area of 2 × 2 um2, the height scale is 20 nm.

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 figure: Fig. 2

Fig. 2 AFM images of GaN QDs annealed under NH3/H2 ambience at 700 °C (a); 750 °C (b); 800 °C (c); 850 °C (d), and GaN QDs annealed under NH3/N2 ambience at 750 °C (e); 800 °C (f); 850 °C (g); 900 °C (h) in scan area of 2 × 2 um2, the height scale for all the images is 20 nm.

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Tables Icon

Table 1. The quantitative statistics of morphologies

For the samples annealed under NH3/N2 ambience, some different behaviors are observed. After the QDs were annealed at 750 °C, the average diameter of the QDs (38 nm) is getting smaller compared with the as-grown ones (40 nm) [Fig. 2(e)], the corresponding height is getting larger (4 nm). And the density is reduced to 3.6 × 1010 cm−2. Unlike the samples annealed under NH3/H2 ambience, the QDs still exist after annealing at 800 °C and 850 °C [Fig. 2(f)-2(g)]. With the increase of annealing temperature to 800 °C, the uniformity is destroyed with the presence of larger GaN QDs (the diameter varies from 40 to 85 nm and the height varies from 1.7 nm to 6 nm) and the density is decreased to 1.3 × 1010 cm−2 accordingly. After the annealing temperature was increased to 850 °C, the patches of GaN “wetting layer” emerge on the surface as what reported by M. Gherasimova et al. [12]. The thickness of these patches is not uniform which varies from 0.55 nm to 0.98 nm. Most of QDs have diameter of 45-68 nm, height of 4.5-5.8 nm and the density is 6.1 × 109 cm−2. The QDs finally disappear with the annealing temperature increased to 900 °C, which is 100°C higher than that under NH3/H2 ambience. These phenomena suggest that NH3/N2 ambience can prevent GaN QDs from decomposition at high temperature, which agrees well with the results of other studies [12].

Indeed, the PGA is a temperature-dependent dynamic balance of several competing mechanisms. During high temperature thermal annealing, some unstable GaN decomposes and Ga droplets escape from their nucleation sites, resulting in the formation of free Ga atoms (GaNGa+N). These free Ga atoms may migrate in the growth front to form larger QDs at stable GaN QDs (Ga+NGaN) or evaporate out [12]. Also, the migration of Ga atoms can be suppressed under sufficient NH3 vapor. Therefore, NH3/N2 ambience is better condition than NH3/H2 in terms of maintaining the QDs morphology by suppressing the migration and evaporation of Ga atoms and preventing the GaN from decomposition. When QDs annealed at lower temperature, the migration and nucleation mechanisms are dominant, leading to the ripening of GaN QDs. As the temperature further increased, the QD structures become more unstable, thus GaN decomposition and Ga evaporation dominate, which cause the disappearance of QDs.

However, GaN material still exists on the surface. As shown in Fig. 3 , X-ray photoelectron spectroscopy (XPS) measurement for samples annealing at 900 °C and 950 °C is carried out. For both samples, the Ga 3d and Ga 2p photoelectron lines were detected. GaN probably change from QDs into a two-dimensional layer at such a high temperature. This indicates that QDs disappear along with the formation of a more stable films on the surface when annealed at relatively high temperature.

 figure: Fig. 3

Fig. 3 XPS survey spectra of samples annealed at 900 °C and 950 °C under H2/NH3 ambient.

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To get better understanding of PGA processes, the chemical bondings of the samples were characterized by XPS. Figure 4 shows the XPS spectra of Ga 3d core level for samples annealed at different conditions. Each peak is further fitted by three sub-peaks, Ga metal from residual metallic Ga, Ga-N and Ga-O with the corresponding binding energy of 18.2 eV [20, 21], 19.9-20.3 eV and 20.7-21 eV [22]. The proportion of Ga metal, Ga-N and Ga-O components in the configuration of Ga 3d core level are listed in Table 2 . These results reveal that the nitridation is enhanced effectively as the annealing temperature rising from 750 °C to 850 °C (800 °C) in NH3/N2 (NH3/H2) ambience, then it fall dramatically at exceedingly high temperature. This can be attributed to the fact that the evaporation of Ga is enhanced and Ga droplet constantly transforms into GaN as the anneal temperature increasing. And at higher temperature, the QDs structure on the growth surface become unstable to decompose. Additionally, the proportion of Ga-N component in the Ga 3d core level of the samples annealed under NH3/H2 ambience are all weaker than those of samples annealed under NH3/N2 ambience at same annealing temperature, which suggests that the NH3/N2 ambience is more helpful to enhance the nitridation. However, for all samples there is still a XPS signal of the Ga-metal which can be seen in Fig. 4. Therefore, we plan to study the in situ N2 plasma treatment to completely transform the Ga droplet into GaN in the further.

 figure: Fig. 4

Fig. 4 XPS spectra from Ga 3d core levels of the GaN QDs annealed at different temperature (a) in H2 ambient, (b) in N2 ambient. Dashed lines correspond to fitted curves for each bond.

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Tables Icon

Table 2. The proportion of Ga-O, Ga-N and Ga metal

To study the influence of PGA on the optical properties of GaN QDs, the room-temperature photoluminescence (PL) excited by 224 nm excitation laser was intensively carried out. Figure 5 displays the PL spectra of surface GaN/AlN QDs and AlN template. It is worth noting that a peak near 295 nm (4.2 eV) is present in AlN template and all the GaN/AlN QDs samples. This peak is origin from the deep level impurity related transition in AlN, as well as the peak near 388 nm (3.2 eV) [23]. When the annealing temperature is not exceeding 750 °C under NH3/N2 ambience, the samples just exhibit the luminescence related to AlN. As the samples are annealed under NH3/N2 at 750 °C and 800 °C, the emission of GaN QDs emerges at 332 nm. With the annealing temperature increased to 850 °C, the luminescence intensity of GaN QDs is further enhanced and the peak shifts to 334 nm, which can be ascribed to the increase of QDs height owing to the ripening process. Because the uncapped GaN QDs is lack of the strain from upper caplayer, the quantum confined stark effect depending on piezoelectric polarizations is weak, which is responsible for the small energy-shift. Thus it can be conclude that the PGA under NH3/N2 at 850 °C can sufficiently improve the optical properties of GaN QDs grown by Ga droplet, which suggests the enhancement of GaN crystal quality.

 figure: Fig. 5

Fig. 5 Room temperature PL spectra of surface GaN QDs.

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However, there is even a problem that the luminescence intensity related to defect of AlN is much larger than that of naked GaN QDs. In order to explain this fact, a model is proposed as shown in Fig. 6 . Indeed, the PL emission at 3.2 eV is a donor-acceptor-pair type transition involving a shallow donor and a V3-/2- deep acceptor [24]. And the 4.2 eV emission is also assigned to the recombination of a shallowly trapped electron with a deeply trapped hole in a (VAl-ON)2-/1- center, which is observed as a ~3.9 eV line due to some coulomb energy on the order of ~0.3 eV [25]. Room temperature band gaps of GaN QDs and AlN template were taken as 3.72 eV and 6.05 eV, respectively. The valence band offset at the GaN/AlN hetero-interface is 0.67 eV (30%). The top of valence band is a reference zero level. The ionization energies (ED) of the shallow donors in AlN are about 86 meV [26]. So, the acceptor level of (VAl-ON)2-/1- is about 1.76 eV. For uncapped GaN QDs, the surface states located within band-gap can be occupied by majority electrons, leading to an upward band bending. Based on the measurements of band bending at GaN (0001) surface reported by Dhesi et al. and Valla et al., this value is 2.1 ± 0.1 eV [27] or about 1.5 eV [28]. The band bending results in a reduced overlap of the wave-functions of photo-generated electrons and holes in GaN QDs. Thus the near band emission of naked GaN QDs becomes weak. However, the level of surface states filling holes is close to that of (VAl-ON)2-/1- center and the reduced probability of forming an exciton in GaN QDs will extend the lifetime of holes at the surface to increase the probability that a hole trapped at the surface tunnels into the acceptor level of (VAl-ON)2-/1- in AlN, which participate in the PL emission through the recombination with the electron in shallow donor. There the emission peak near 4.2 eV can be greatly enhanced.

 figure: Fig. 6

Fig. 6 A schematic energy diagram about the band alignment of surface GaN/AlN QDs

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4. Conclusion

In summary, the influence of high-temperature PGA under NH3/H2 and NH3/N2 ambience on the surface morphology and nitridation degree of GaN QDs grown via Ga droplet has been analyzed. The PGA is a temperature-dependent dynamic balance of GaN decomposition, Ga atoms migration, nucleation and evaporation out. As the temperature increased within a certain scope of temperature, the degree of nitridation of the GaN QDs is constantly enhanced regardless of the annealing ambience, which is mainly the result of the residual Ga atoms migration and nucleation. When the annealing temperature is too high, the GaN QDs will transform into GaN film due to the coaction of the decomposition of QDs, migration and nucleation of Ga atoms. Moreover, the PGA ambiences have also affected the dot formation on the surface significantly, and a NH3/N2 ambience is demonstrated as a necessary condition for maintaining optimal QDs morphology by suppressing the migration and evaporation of Ga atoms and preventing the GaN decomposition.

Acknowledgments

This work is supported by the National Basic Research Program of China (Grant No. 2012CB619302), the National Natural Science Foundation of China (Grant No.61405076), the Science and Technology Bureau of Wuhan City (No.2014010101010003), the Natural Science Foundation of Hubei Province (Grant No.2014CFB175) and the Open Project of National Laboratory for Infrared Physics is affiliated with Shanghai Institute of Technical Physics, Chinese Academy of Sciences (Grant No.IIMDKFJJ-13-04). Thanks the Center of Micro-Fabrication and Characterization (CMFC) of WNLO for the support of AFM measurement. Thanks Guozhen Zhang, the PhD student at Wuhan University, for the support of PL measurement.

References and links

1. W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014). [PubMed]  

2. J. Verma, S. M. Islam, V. Protasenko, P. K. Kandaswamy, H. L. Xing, and D. Jena, “Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures,” Appl. Phys. Lett. 104(2), 021105 (2014). [CrossRef]  

3. S. Kako, C. Santori, K. Hoshino, S. Götzinger, Y. Yamamoto, and Y. Arakawa, “A gallium nitride single-photon source operating at 200 K,” Nat. Mater. 5(11), 887–892 (2006). [CrossRef]   [PubMed]  

4. K. Kawasaki, D. Yamazaki, A. Kinoshita, H. Hirayama, K. Tsutsui, and Y. Aoyagi, “GaN quantum-dot formation by self-assembling droplet epitaxy and application to single-electron transistors,” Appl. Phys. Lett. 79(14), 2243–2245 (2001). [CrossRef]  

5. P. Dimitrakis, P. Normand, V. Ioannou-Sougleridis, C. Bonafos, S. Schamm-Chardon, G. BenAssayag, and E. Iliopoulos, “Quantum dots for memory applications,” Phys. Status Solidi210(8), 1490–1504 (2013) (a). [CrossRef]  

6. A. Asgari and S. Razi, “High performances III-Nitride Quantum Dot infrared photodetector operating at room temperature,” Opt. Express 18(14), 14604–14615 (2010). [CrossRef]   [PubMed]  

7. T. Huault, J. Brault, F. Natali, B. Damilano, D. Lefebvre, L. Nguyen, M. Leroux, and J. Massies, “Blue-light emission from GaN/Al[sub 0.5]Ga[sub 0.5]N quantum dots,” Appl. Phys. Lett. 92(5), 051911 (2008). [CrossRef]  

8. F. Widmann, J. Simon, B. Daudin, G. Feuillet, J. L. Rouviere, N. T. Pelekanos, and G. Fishman, “Blue-light emission from GaN self-assembled quantum dots due to giant piezoelectric effect,” Phys. Rev. B 58(24), 15989 (1998). [CrossRef]  

9. C. W. Hu, A. Bell, F. A. Ponce, D. J. Smith, and I. S. T. Tsong, “Growth of self-assembled GaN quantum dots via the vapor–liquid–solid mechanism,” Appl. Phys. Lett. 81(17), 3236 (2002). [CrossRef]  

10. T. Kondo, K. Saitoh, Y. Yamamoto, T. Maruyama, and S. Naritsuka, “Fabrication of GaN dot structures on Si substrates by droplet epitaxy,” Physica Status Solidi a-Applications and Materials Science. 203(7), 1700–1703 (2006). [CrossRef]  

11. R. K. Debnath, T. Stoica, A. Besmehn, K. Jeganathan, E. Sutter, R. Meijers, H. Luth, and R. Calarco, “Formation of GaN nanodots on Si (111) by droplet nitridation,” J. Cryst. Growth 311(13), 3389–3394 (2009). [CrossRef]  

12. M. Gherasimova, G. Cui, S. R. Jeon, Z. Ren, D. Martos, J. Han, Y. He, and A. V. Nurmikko, “Droplet heteroepitaxy of GaN quantum dots by metal-organic chemical vapor deposition,” Appl. Phys. Lett. 85(12), 2346–2348 (2004). [CrossRef]  

13. M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010). [CrossRef]  

14. J. C. Zhang, B. Meyler, A. Vardi, G. Bahir, and J. Salzman, “Stranski–Krastanov growth of GaN quantum dots on AlN template by metalorganic chemical vapor deposition,” J. Appl. Phys. 104(4), 044307 (2008). [CrossRef]  

15. K. Hoshino and Y. Arakawa, “Effect of thermal treatment on structure of GaN self-assembled quantum dots grown by MOCVD,” 2nd International Conference on Semiconductor Quantum Dots0(4), 1101–1104 (2003). [CrossRef]  

16. H. Wang, S. L. Li, H. Xiong, Z. H. Wu, J. N. Dai, Y. Tian, Y. Y. Fang, and C. Q. Chen, “The effect of AlN nucleation temperature on the growth of AlN films via metalorganic chemical vapor deposition,” J. Electron. Mater. 41(3), 466–470 (2012). [CrossRef]  

17. A. Raab and G. Springholz, “Oswald ripening and shape transitions of self-assembled PbSe quantum dots on PbTe (111) during annealing,” Appl. Phys. Lett. 77(19), 2991–2993 (2000). [CrossRef]  

18. X. Hui, J. Zhang, S. Li, H. Wang, Y. Fang, J. Dai, and C. Chen, “Fabrication of GaN nanodots via GaN thermal decomposition in H2 atmosphere,” J. Vac. Sci. Technol. B 31(5), 050607 (2013). [CrossRef]  

19. Y. Morimoto, “Few Characteristics of Epitaxial GaN—Etching and Thermal Decomposition,” J. Electrochem. Soc. 121(10), 1383–1384 (1974). [CrossRef]  

20. J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013). [CrossRef]  

21. J. Massies and J. P. Contour, “Substrate chemical etching prior to molecular-beam epitaxy: An x-ray photoelectron spectroscopy study of GaAs {001} surfaces etched by the H2SO4-H2O2-H2O solution,” J. Appl. Phys. 58(2), 806 (1985). [CrossRef]  

22. A. N. Hattori, F. Kawamura, M. Yoshimura, Y. Kitaoka, Y. Mori, K. Hattori, H. Daimon, and K. Endo, “Chemical etchant dependence of surface structure and morphology on GaN(0001) substrates,” Surf. Sci. 604(15–16), 1247–1253 (2010). [CrossRef]  

23. J. Li, K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Band-edge photoluminescence of AlN epilayers,” Appl. Phys. Lett. 81(18), 3365 (2002). [CrossRef]  

24. A. Sedhain, L. Du, J. H. Edgar, J. Y. Lin, and H. X. Jiang, “The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates,” Appl. Phys. Lett. 95(26), 262104 (2009). [CrossRef]  

25. A. Sedhain, J. Y. Lin, and H. X. Jiang, “Nature of optical transitions involving cation vacancies and complexes in AlN and AlGaN,” Appl. Phys. Lett. 100(22), 221107 (2012). [CrossRef]  

26. K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Deep impurity transitions involving cation vacancies and complexes in AlGaN alloys,” Appl. Phys. Lett. 86(22), 222108 (2005). [CrossRef]  

27. S. S. Dhesi, C. B. Stagarescu, K. E. Smith, D. Doppalapudi, R. Singh, and T. D. Moustakas, “Surface and bulk electronic structure of thin-film wurtzite GaN,” Phys. Rev. B 56(16), 10271–10275 (1997). [CrossRef]  

28. T. Valla, P. D. Johnson, S. S. Dhesi, K. E. Smith, D. Doppalapudi, T. D. Moustakas, and E. L. Shirley, “Unoccupied band structure of wurtzite GaN(0001),” Phys. Rev. B 59(7), 5003–5007 (1999). [CrossRef]  

References

  • View by:

  1. W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
    [PubMed]
  2. J. Verma, S. M. Islam, V. Protasenko, P. K. Kandaswamy, H. L. Xing, and D. Jena, “Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures,” Appl. Phys. Lett. 104(2), 021105 (2014).
    [Crossref]
  3. S. Kako, C. Santori, K. Hoshino, S. Götzinger, Y. Yamamoto, and Y. Arakawa, “A gallium nitride single-photon source operating at 200 K,” Nat. Mater. 5(11), 887–892 (2006).
    [Crossref] [PubMed]
  4. K. Kawasaki, D. Yamazaki, A. Kinoshita, H. Hirayama, K. Tsutsui, and Y. Aoyagi, “GaN quantum-dot formation by self-assembling droplet epitaxy and application to single-electron transistors,” Appl. Phys. Lett. 79(14), 2243–2245 (2001).
    [Crossref]
  5. P. Dimitrakis, P. Normand, V. Ioannou-Sougleridis, C. Bonafos, S. Schamm-Chardon, G. BenAssayag, and E. Iliopoulos, “Quantum dots for memory applications,” Phys. Status Solidi210(8), 1490–1504 (2013) (a).
    [Crossref]
  6. A. Asgari and S. Razi, “High performances III-Nitride Quantum Dot infrared photodetector operating at room temperature,” Opt. Express 18(14), 14604–14615 (2010).
    [Crossref] [PubMed]
  7. T. Huault, J. Brault, F. Natali, B. Damilano, D. Lefebvre, L. Nguyen, M. Leroux, and J. Massies, “Blue-light emission from GaN/Al[sub 0.5]Ga[sub 0.5]N quantum dots,” Appl. Phys. Lett. 92(5), 051911 (2008).
    [Crossref]
  8. F. Widmann, J. Simon, B. Daudin, G. Feuillet, J. L. Rouviere, N. T. Pelekanos, and G. Fishman, “Blue-light emission from GaN self-assembled quantum dots due to giant piezoelectric effect,” Phys. Rev. B 58(24), 15989 (1998).
    [Crossref]
  9. C. W. Hu, A. Bell, F. A. Ponce, D. J. Smith, and I. S. T. Tsong, “Growth of self-assembled GaN quantum dots via the vapor–liquid–solid mechanism,” Appl. Phys. Lett. 81(17), 3236 (2002).
    [Crossref]
  10. T. Kondo, K. Saitoh, Y. Yamamoto, T. Maruyama, and S. Naritsuka, “Fabrication of GaN dot structures on Si substrates by droplet epitaxy,” Physica Status Solidi a-Applications and Materials Science. 203(7), 1700–1703 (2006).
    [Crossref]
  11. R. K. Debnath, T. Stoica, A. Besmehn, K. Jeganathan, E. Sutter, R. Meijers, H. Luth, and R. Calarco, “Formation of GaN nanodots on Si (111) by droplet nitridation,” J. Cryst. Growth 311(13), 3389–3394 (2009).
    [Crossref]
  12. M. Gherasimova, G. Cui, S. R. Jeon, Z. Ren, D. Martos, J. Han, Y. He, and A. V. Nurmikko, “Droplet heteroepitaxy of GaN quantum dots by metal-organic chemical vapor deposition,” Appl. Phys. Lett. 85(12), 2346–2348 (2004).
    [Crossref]
  13. M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010).
    [Crossref]
  14. J. C. Zhang, B. Meyler, A. Vardi, G. Bahir, and J. Salzman, “Stranski–Krastanov growth of GaN quantum dots on AlN template by metalorganic chemical vapor deposition,” J. Appl. Phys. 104(4), 044307 (2008).
    [Crossref]
  15. K. Hoshino and Y. Arakawa, “Effect of thermal treatment on structure of GaN self-assembled quantum dots grown by MOCVD,” 2nd International Conference on Semiconductor Quantum Dots0(4), 1101–1104 (2003).
    [Crossref]
  16. H. Wang, S. L. Li, H. Xiong, Z. H. Wu, J. N. Dai, Y. Tian, Y. Y. Fang, and C. Q. Chen, “The effect of AlN nucleation temperature on the growth of AlN films via metalorganic chemical vapor deposition,” J. Electron. Mater. 41(3), 466–470 (2012).
    [Crossref]
  17. A. Raab and G. Springholz, “Oswald ripening and shape transitions of self-assembled PbSe quantum dots on PbTe (111) during annealing,” Appl. Phys. Lett. 77(19), 2991–2993 (2000).
    [Crossref]
  18. X. Hui, J. Zhang, S. Li, H. Wang, Y. Fang, J. Dai, and C. Chen, “Fabrication of GaN nanodots via GaN thermal decomposition in H2 atmosphere,” J. Vac. Sci. Technol. B 31(5), 050607 (2013).
    [Crossref]
  19. Y. Morimoto, “Few Characteristics of Epitaxial GaN—Etching and Thermal Decomposition,” J. Electrochem. Soc. 121(10), 1383–1384 (1974).
    [Crossref]
  20. J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013).
    [Crossref]
  21. J. Massies and J. P. Contour, “Substrate chemical etching prior to molecular-beam epitaxy: An x-ray photoelectron spectroscopy study of GaAs {001} surfaces etched by the H2SO4-H2O2-H2O solution,” J. Appl. Phys. 58(2), 806 (1985).
    [Crossref]
  22. A. N. Hattori, F. Kawamura, M. Yoshimura, Y. Kitaoka, Y. Mori, K. Hattori, H. Daimon, and K. Endo, “Chemical etchant dependence of surface structure and morphology on GaN(0001) substrates,” Surf. Sci. 604(15–16), 1247–1253 (2010).
    [Crossref]
  23. J. Li, K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Band-edge photoluminescence of AlN epilayers,” Appl. Phys. Lett. 81(18), 3365 (2002).
    [Crossref]
  24. A. Sedhain, L. Du, J. H. Edgar, J. Y. Lin, and H. X. Jiang, “The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates,” Appl. Phys. Lett. 95(26), 262104 (2009).
    [Crossref]
  25. A. Sedhain, J. Y. Lin, and H. X. Jiang, “Nature of optical transitions involving cation vacancies and complexes in AlN and AlGaN,” Appl. Phys. Lett. 100(22), 221107 (2012).
    [Crossref]
  26. K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Deep impurity transitions involving cation vacancies and complexes in AlGaN alloys,” Appl. Phys. Lett. 86(22), 222108 (2005).
    [Crossref]
  27. S. S. Dhesi, C. B. Stagarescu, K. E. Smith, D. Doppalapudi, R. Singh, and T. D. Moustakas, “Surface and bulk electronic structure of thin-film wurtzite GaN,” Phys. Rev. B 56(16), 10271–10275 (1997).
    [Crossref]
  28. T. Valla, P. D. Johnson, S. S. Dhesi, K. E. Smith, D. Doppalapudi, T. D. Moustakas, and E. L. Shirley, “Unoccupied band structure of wurtzite GaN(0001),” Phys. Rev. B 59(7), 5003–5007 (1999).
    [Crossref]

2014 (2)

W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
[PubMed]

J. Verma, S. M. Islam, V. Protasenko, P. K. Kandaswamy, H. L. Xing, and D. Jena, “Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures,” Appl. Phys. Lett. 104(2), 021105 (2014).
[Crossref]

2013 (2)

X. Hui, J. Zhang, S. Li, H. Wang, Y. Fang, J. Dai, and C. Chen, “Fabrication of GaN nanodots via GaN thermal decomposition in H2 atmosphere,” J. Vac. Sci. Technol. B 31(5), 050607 (2013).
[Crossref]

J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013).
[Crossref]

2012 (2)

A. Sedhain, J. Y. Lin, and H. X. Jiang, “Nature of optical transitions involving cation vacancies and complexes in AlN and AlGaN,” Appl. Phys. Lett. 100(22), 221107 (2012).
[Crossref]

H. Wang, S. L. Li, H. Xiong, Z. H. Wu, J. N. Dai, Y. Tian, Y. Y. Fang, and C. Q. Chen, “The effect of AlN nucleation temperature on the growth of AlN films via metalorganic chemical vapor deposition,” J. Electron. Mater. 41(3), 466–470 (2012).
[Crossref]

2010 (3)

M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010).
[Crossref]

A. Asgari and S. Razi, “High performances III-Nitride Quantum Dot infrared photodetector operating at room temperature,” Opt. Express 18(14), 14604–14615 (2010).
[Crossref] [PubMed]

A. N. Hattori, F. Kawamura, M. Yoshimura, Y. Kitaoka, Y. Mori, K. Hattori, H. Daimon, and K. Endo, “Chemical etchant dependence of surface structure and morphology on GaN(0001) substrates,” Surf. Sci. 604(15–16), 1247–1253 (2010).
[Crossref]

2009 (2)

A. Sedhain, L. Du, J. H. Edgar, J. Y. Lin, and H. X. Jiang, “The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates,” Appl. Phys. Lett. 95(26), 262104 (2009).
[Crossref]

R. K. Debnath, T. Stoica, A. Besmehn, K. Jeganathan, E. Sutter, R. Meijers, H. Luth, and R. Calarco, “Formation of GaN nanodots on Si (111) by droplet nitridation,” J. Cryst. Growth 311(13), 3389–3394 (2009).
[Crossref]

2008 (2)

J. C. Zhang, B. Meyler, A. Vardi, G. Bahir, and J. Salzman, “Stranski–Krastanov growth of GaN quantum dots on AlN template by metalorganic chemical vapor deposition,” J. Appl. Phys. 104(4), 044307 (2008).
[Crossref]

T. Huault, J. Brault, F. Natali, B. Damilano, D. Lefebvre, L. Nguyen, M. Leroux, and J. Massies, “Blue-light emission from GaN/Al[sub 0.5]Ga[sub 0.5]N quantum dots,” Appl. Phys. Lett. 92(5), 051911 (2008).
[Crossref]

2006 (2)

T. Kondo, K. Saitoh, Y. Yamamoto, T. Maruyama, and S. Naritsuka, “Fabrication of GaN dot structures on Si substrates by droplet epitaxy,” Physica Status Solidi a-Applications and Materials Science. 203(7), 1700–1703 (2006).
[Crossref]

S. Kako, C. Santori, K. Hoshino, S. Götzinger, Y. Yamamoto, and Y. Arakawa, “A gallium nitride single-photon source operating at 200 K,” Nat. Mater. 5(11), 887–892 (2006).
[Crossref] [PubMed]

2005 (1)

K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Deep impurity transitions involving cation vacancies and complexes in AlGaN alloys,” Appl. Phys. Lett. 86(22), 222108 (2005).
[Crossref]

2004 (1)

M. Gherasimova, G. Cui, S. R. Jeon, Z. Ren, D. Martos, J. Han, Y. He, and A. V. Nurmikko, “Droplet heteroepitaxy of GaN quantum dots by metal-organic chemical vapor deposition,” Appl. Phys. Lett. 85(12), 2346–2348 (2004).
[Crossref]

2002 (2)

C. W. Hu, A. Bell, F. A. Ponce, D. J. Smith, and I. S. T. Tsong, “Growth of self-assembled GaN quantum dots via the vapor–liquid–solid mechanism,” Appl. Phys. Lett. 81(17), 3236 (2002).
[Crossref]

J. Li, K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Band-edge photoluminescence of AlN epilayers,” Appl. Phys. Lett. 81(18), 3365 (2002).
[Crossref]

2001 (1)

K. Kawasaki, D. Yamazaki, A. Kinoshita, H. Hirayama, K. Tsutsui, and Y. Aoyagi, “GaN quantum-dot formation by self-assembling droplet epitaxy and application to single-electron transistors,” Appl. Phys. Lett. 79(14), 2243–2245 (2001).
[Crossref]

2000 (1)

A. Raab and G. Springholz, “Oswald ripening and shape transitions of self-assembled PbSe quantum dots on PbTe (111) during annealing,” Appl. Phys. Lett. 77(19), 2991–2993 (2000).
[Crossref]

1999 (1)

T. Valla, P. D. Johnson, S. S. Dhesi, K. E. Smith, D. Doppalapudi, T. D. Moustakas, and E. L. Shirley, “Unoccupied band structure of wurtzite GaN(0001),” Phys. Rev. B 59(7), 5003–5007 (1999).
[Crossref]

1998 (1)

F. Widmann, J. Simon, B. Daudin, G. Feuillet, J. L. Rouviere, N. T. Pelekanos, and G. Fishman, “Blue-light emission from GaN self-assembled quantum dots due to giant piezoelectric effect,” Phys. Rev. B 58(24), 15989 (1998).
[Crossref]

1997 (1)

S. S. Dhesi, C. B. Stagarescu, K. E. Smith, D. Doppalapudi, R. Singh, and T. D. Moustakas, “Surface and bulk electronic structure of thin-film wurtzite GaN,” Phys. Rev. B 56(16), 10271–10275 (1997).
[Crossref]

1985 (1)

J. Massies and J. P. Contour, “Substrate chemical etching prior to molecular-beam epitaxy: An x-ray photoelectron spectroscopy study of GaAs {001} surfaces etched by the H2SO4-H2O2-H2O solution,” J. Appl. Phys. 58(2), 806 (1985).
[Crossref]

1974 (1)

Y. Morimoto, “Few Characteristics of Epitaxial GaN—Etching and Thermal Decomposition,” J. Electrochem. Soc. 121(10), 1383–1384 (1974).
[Crossref]

Alves, E.

M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010).
[Crossref]

Aoyagi, Y.

K. Kawasaki, D. Yamazaki, A. Kinoshita, H. Hirayama, K. Tsutsui, and Y. Aoyagi, “GaN quantum-dot formation by self-assembling droplet epitaxy and application to single-electron transistors,” Appl. Phys. Lett. 79(14), 2243–2245 (2001).
[Crossref]

Arakawa, Y.

S. Kako, C. Santori, K. Hoshino, S. Götzinger, Y. Yamamoto, and Y. Arakawa, “A gallium nitride single-photon source operating at 200 K,” Nat. Mater. 5(11), 887–892 (2006).
[Crossref] [PubMed]

K. Hoshino and Y. Arakawa, “Effect of thermal treatment on structure of GaN self-assembled quantum dots grown by MOCVD,” 2nd International Conference on Semiconductor Quantum Dots0(4), 1101–1104 (2003).
[Crossref]

Asgari, A.

Bahir, G.

J. C. Zhang, B. Meyler, A. Vardi, G. Bahir, and J. Salzman, “Stranski–Krastanov growth of GaN quantum dots on AlN template by metalorganic chemical vapor deposition,” J. Appl. Phys. 104(4), 044307 (2008).
[Crossref]

Bell, A.

C. W. Hu, A. Bell, F. A. Ponce, D. J. Smith, and I. S. T. Tsong, “Growth of self-assembled GaN quantum dots via the vapor–liquid–solid mechanism,” Appl. Phys. Lett. 81(17), 3236 (2002).
[Crossref]

BenAssayag, G.

P. Dimitrakis, P. Normand, V. Ioannou-Sougleridis, C. Bonafos, S. Schamm-Chardon, G. BenAssayag, and E. Iliopoulos, “Quantum dots for memory applications,” Phys. Status Solidi210(8), 1490–1504 (2013) (a).
[Crossref]

Besmehn, A.

R. K. Debnath, T. Stoica, A. Besmehn, K. Jeganathan, E. Sutter, R. Meijers, H. Luth, and R. Calarco, “Formation of GaN nanodots on Si (111) by droplet nitridation,” J. Cryst. Growth 311(13), 3389–3394 (2009).
[Crossref]

Bonafos, C.

P. Dimitrakis, P. Normand, V. Ioannou-Sougleridis, C. Bonafos, S. Schamm-Chardon, G. BenAssayag, and E. Iliopoulos, “Quantum dots for memory applications,” Phys. Status Solidi210(8), 1490–1504 (2013) (a).
[Crossref]

Bougerol, C.

M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010).
[Crossref]

Brault, J.

T. Huault, J. Brault, F. Natali, B. Damilano, D. Lefebvre, L. Nguyen, M. Leroux, and J. Massies, “Blue-light emission from GaN/Al[sub 0.5]Ga[sub 0.5]N quantum dots,” Appl. Phys. Lett. 92(5), 051911 (2008).
[Crossref]

Calarco, R.

R. K. Debnath, T. Stoica, A. Besmehn, K. Jeganathan, E. Sutter, R. Meijers, H. Luth, and R. Calarco, “Formation of GaN nanodots on Si (111) by droplet nitridation,” J. Cryst. Growth 311(13), 3389–3394 (2009).
[Crossref]

Chang, T. C.

J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013).
[Crossref]

Chen, C.

X. Hui, J. Zhang, S. Li, H. Wang, Y. Fang, J. Dai, and C. Chen, “Fabrication of GaN nanodots via GaN thermal decomposition in H2 atmosphere,” J. Vac. Sci. Technol. B 31(5), 050607 (2013).
[Crossref]

Chen, C. Q.

H. Wang, S. L. Li, H. Xiong, Z. H. Wu, J. N. Dai, Y. Tian, Y. Y. Fang, and C. Q. Chen, “The effect of AlN nucleation temperature on the growth of AlN films via metalorganic chemical vapor deposition,” J. Electron. Mater. 41(3), 466–470 (2012).
[Crossref]

Chen, H.

W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
[PubMed]

Chen, S. C.

J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013).
[Crossref]

Chen, Y. T.

J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013).
[Crossref]

Chu, A. K.

J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013).
[Crossref]

Contour, J. P.

J. Massies and J. P. Contour, “Substrate chemical etching prior to molecular-beam epitaxy: An x-ray photoelectron spectroscopy study of GaAs {001} surfaces etched by the H2SO4-H2O2-H2O solution,” J. Appl. Phys. 58(2), 806 (1985).
[Crossref]

Cui, G.

M. Gherasimova, G. Cui, S. R. Jeon, Z. Ren, D. Martos, J. Han, Y. He, and A. V. Nurmikko, “Droplet heteroepitaxy of GaN quantum dots by metal-organic chemical vapor deposition,” Appl. Phys. Lett. 85(12), 2346–2348 (2004).
[Crossref]

Dai, J.

X. Hui, J. Zhang, S. Li, H. Wang, Y. Fang, J. Dai, and C. Chen, “Fabrication of GaN nanodots via GaN thermal decomposition in H2 atmosphere,” J. Vac. Sci. Technol. B 31(5), 050607 (2013).
[Crossref]

Dai, J. N.

H. Wang, S. L. Li, H. Xiong, Z. H. Wu, J. N. Dai, Y. Tian, Y. Y. Fang, and C. Q. Chen, “The effect of AlN nucleation temperature on the growth of AlN films via metalorganic chemical vapor deposition,” J. Electron. Mater. 41(3), 466–470 (2012).
[Crossref]

Daimon, H.

A. N. Hattori, F. Kawamura, M. Yoshimura, Y. Kitaoka, Y. Mori, K. Hattori, H. Daimon, and K. Endo, “Chemical etchant dependence of surface structure and morphology on GaN(0001) substrates,” Surf. Sci. 604(15–16), 1247–1253 (2010).
[Crossref]

Damilano, B.

T. Huault, J. Brault, F. Natali, B. Damilano, D. Lefebvre, L. Nguyen, M. Leroux, and J. Massies, “Blue-light emission from GaN/Al[sub 0.5]Ga[sub 0.5]N quantum dots,” Appl. Phys. Lett. 92(5), 051911 (2008).
[Crossref]

Daudin, B.

M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010).
[Crossref]

F. Widmann, J. Simon, B. Daudin, G. Feuillet, J. L. Rouviere, N. T. Pelekanos, and G. Fishman, “Blue-light emission from GaN self-assembled quantum dots due to giant piezoelectric effect,” Phys. Rev. B 58(24), 15989 (1998).
[Crossref]

Debnath, R. K.

R. K. Debnath, T. Stoica, A. Besmehn, K. Jeganathan, E. Sutter, R. Meijers, H. Luth, and R. Calarco, “Formation of GaN nanodots on Si (111) by droplet nitridation,” J. Cryst. Growth 311(13), 3389–3394 (2009).
[Crossref]

Dhesi, S. S.

T. Valla, P. D. Johnson, S. S. Dhesi, K. E. Smith, D. Doppalapudi, T. D. Moustakas, and E. L. Shirley, “Unoccupied band structure of wurtzite GaN(0001),” Phys. Rev. B 59(7), 5003–5007 (1999).
[Crossref]

S. S. Dhesi, C. B. Stagarescu, K. E. Smith, D. Doppalapudi, R. Singh, and T. D. Moustakas, “Surface and bulk electronic structure of thin-film wurtzite GaN,” Phys. Rev. B 56(16), 10271–10275 (1997).
[Crossref]

Dimitrakis, P.

P. Dimitrakis, P. Normand, V. Ioannou-Sougleridis, C. Bonafos, S. Schamm-Chardon, G. BenAssayag, and E. Iliopoulos, “Quantum dots for memory applications,” Phys. Status Solidi210(8), 1490–1504 (2013) (a).
[Crossref]

Doppalapudi, D.

T. Valla, P. D. Johnson, S. S. Dhesi, K. E. Smith, D. Doppalapudi, T. D. Moustakas, and E. L. Shirley, “Unoccupied band structure of wurtzite GaN(0001),” Phys. Rev. B 59(7), 5003–5007 (1999).
[Crossref]

S. S. Dhesi, C. B. Stagarescu, K. E. Smith, D. Doppalapudi, R. Singh, and T. D. Moustakas, “Surface and bulk electronic structure of thin-film wurtzite GaN,” Phys. Rev. B 56(16), 10271–10275 (1997).
[Crossref]

Du, L.

A. Sedhain, L. Du, J. H. Edgar, J. Y. Lin, and H. X. Jiang, “The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates,” Appl. Phys. Lett. 95(26), 262104 (2009).
[Crossref]

Edgar, J. H.

A. Sedhain, L. Du, J. H. Edgar, J. Y. Lin, and H. X. Jiang, “The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates,” Appl. Phys. Lett. 95(26), 262104 (2009).
[Crossref]

Endo, K.

A. N. Hattori, F. Kawamura, M. Yoshimura, Y. Kitaoka, Y. Mori, K. Hattori, H. Daimon, and K. Endo, “Chemical etchant dependence of surface structure and morphology on GaN(0001) substrates,” Surf. Sci. 604(15–16), 1247–1253 (2010).
[Crossref]

Fang, Y.

X. Hui, J. Zhang, S. Li, H. Wang, Y. Fang, J. Dai, and C. Chen, “Fabrication of GaN nanodots via GaN thermal decomposition in H2 atmosphere,” J. Vac. Sci. Technol. B 31(5), 050607 (2013).
[Crossref]

Fang, Y. Y.

H. Wang, S. L. Li, H. Xiong, Z. H. Wu, J. N. Dai, Y. Tian, Y. Y. Fang, and C. Q. Chen, “The effect of AlN nucleation temperature on the growth of AlN films via metalorganic chemical vapor deposition,” J. Electron. Mater. 41(3), 466–470 (2012).
[Crossref]

Fellmann, V.

M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010).
[Crossref]

Feuillet, G.

F. Widmann, J. Simon, B. Daudin, G. Feuillet, J. L. Rouviere, N. T. Pelekanos, and G. Fishman, “Blue-light emission from GaN self-assembled quantum dots due to giant piezoelectric effect,” Phys. Rev. B 58(24), 15989 (1998).
[Crossref]

Fishman, G.

F. Widmann, J. Simon, B. Daudin, G. Feuillet, J. L. Rouviere, N. T. Pelekanos, and G. Fishman, “Blue-light emission from GaN self-assembled quantum dots due to giant piezoelectric effect,” Phys. Rev. B 58(24), 15989 (1998).
[Crossref]

Gherasimova, M.

M. Gherasimova, G. Cui, S. R. Jeon, Z. Ren, D. Martos, J. Han, Y. He, and A. V. Nurmikko, “Droplet heteroepitaxy of GaN quantum dots by metal-organic chemical vapor deposition,” Appl. Phys. Lett. 85(12), 2346–2348 (2004).
[Crossref]

Götzinger, S.

S. Kako, C. Santori, K. Hoshino, S. Götzinger, Y. Yamamoto, and Y. Arakawa, “A gallium nitride single-photon source operating at 200 K,” Nat. Mater. 5(11), 887–892 (2006).
[Crossref] [PubMed]

Han, J.

M. Gherasimova, G. Cui, S. R. Jeon, Z. Ren, D. Martos, J. Han, Y. He, and A. V. Nurmikko, “Droplet heteroepitaxy of GaN quantum dots by metal-organic chemical vapor deposition,” Appl. Phys. Lett. 85(12), 2346–2348 (2004).
[Crossref]

Hattori, A. N.

A. N. Hattori, F. Kawamura, M. Yoshimura, Y. Kitaoka, Y. Mori, K. Hattori, H. Daimon, and K. Endo, “Chemical etchant dependence of surface structure and morphology on GaN(0001) substrates,” Surf. Sci. 604(15–16), 1247–1253 (2010).
[Crossref]

Hattori, K.

A. N. Hattori, F. Kawamura, M. Yoshimura, Y. Kitaoka, Y. Mori, K. Hattori, H. Daimon, and K. Endo, “Chemical etchant dependence of surface structure and morphology on GaN(0001) substrates,” Surf. Sci. 604(15–16), 1247–1253 (2010).
[Crossref]

He, Y.

M. Gherasimova, G. Cui, S. R. Jeon, Z. Ren, D. Martos, J. Han, Y. He, and A. V. Nurmikko, “Droplet heteroepitaxy of GaN quantum dots by metal-organic chemical vapor deposition,” Appl. Phys. Lett. 85(12), 2346–2348 (2004).
[Crossref]

Hirayama, H.

K. Kawasaki, D. Yamazaki, A. Kinoshita, H. Hirayama, K. Tsutsui, and Y. Aoyagi, “GaN quantum-dot formation by self-assembling droplet epitaxy and application to single-electron transistors,” Appl. Phys. Lett. 79(14), 2243–2245 (2001).
[Crossref]

Hoshino, K.

S. Kako, C. Santori, K. Hoshino, S. Götzinger, Y. Yamamoto, and Y. Arakawa, “A gallium nitride single-photon source operating at 200 K,” Nat. Mater. 5(11), 887–892 (2006).
[Crossref] [PubMed]

K. Hoshino and Y. Arakawa, “Effect of thermal treatment on structure of GaN self-assembled quantum dots grown by MOCVD,” 2nd International Conference on Semiconductor Quantum Dots0(4), 1101–1104 (2003).
[Crossref]

Hu, C. W.

C. W. Hu, A. Bell, F. A. Ponce, D. J. Smith, and I. S. T. Tsong, “Growth of self-assembled GaN quantum dots via the vapor–liquid–solid mechanism,” Appl. Phys. Lett. 81(17), 3236 (2002).
[Crossref]

Huang, J. J.

J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013).
[Crossref]

Huang, P. K.

W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
[PubMed]

Huault, T.

T. Huault, J. Brault, F. Natali, B. Damilano, D. Lefebvre, L. Nguyen, M. Leroux, and J. Massies, “Blue-light emission from GaN/Al[sub 0.5]Ga[sub 0.5]N quantum dots,” Appl. Phys. Lett. 92(5), 051911 (2008).
[Crossref]

Hui, X.

X. Hui, J. Zhang, S. Li, H. Wang, Y. Fang, J. Dai, and C. Chen, “Fabrication of GaN nanodots via GaN thermal decomposition in H2 atmosphere,” J. Vac. Sci. Technol. B 31(5), 050607 (2013).
[Crossref]

Iliopoulos, E.

P. Dimitrakis, P. Normand, V. Ioannou-Sougleridis, C. Bonafos, S. Schamm-Chardon, G. BenAssayag, and E. Iliopoulos, “Quantum dots for memory applications,” Phys. Status Solidi210(8), 1490–1504 (2013) (a).
[Crossref]

Ioannou-Sougleridis, V.

P. Dimitrakis, P. Normand, V. Ioannou-Sougleridis, C. Bonafos, S. Schamm-Chardon, G. BenAssayag, and E. Iliopoulos, “Quantum dots for memory applications,” Phys. Status Solidi210(8), 1490–1504 (2013) (a).
[Crossref]

Islam, S. M.

J. Verma, S. M. Islam, V. Protasenko, P. K. Kandaswamy, H. L. Xing, and D. Jena, “Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures,” Appl. Phys. Lett. 104(2), 021105 (2014).
[Crossref]

Jeganathan, K.

R. K. Debnath, T. Stoica, A. Besmehn, K. Jeganathan, E. Sutter, R. Meijers, H. Luth, and R. Calarco, “Formation of GaN nanodots on Si (111) by droplet nitridation,” J. Cryst. Growth 311(13), 3389–3394 (2009).
[Crossref]

Jena, D.

J. Verma, S. M. Islam, V. Protasenko, P. K. Kandaswamy, H. L. Xing, and D. Jena, “Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures,” Appl. Phys. Lett. 104(2), 021105 (2014).
[Crossref]

Jeon, S. R.

M. Gherasimova, G. Cui, S. R. Jeon, Z. Ren, D. Martos, J. Han, Y. He, and A. V. Nurmikko, “Droplet heteroepitaxy of GaN quantum dots by metal-organic chemical vapor deposition,” Appl. Phys. Lett. 85(12), 2346–2348 (2004).
[Crossref]

Jiang, H. X.

A. Sedhain, J. Y. Lin, and H. X. Jiang, “Nature of optical transitions involving cation vacancies and complexes in AlN and AlGaN,” Appl. Phys. Lett. 100(22), 221107 (2012).
[Crossref]

A. Sedhain, L. Du, J. H. Edgar, J. Y. Lin, and H. X. Jiang, “The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates,” Appl. Phys. Lett. 95(26), 262104 (2009).
[Crossref]

K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Deep impurity transitions involving cation vacancies and complexes in AlGaN alloys,” Appl. Phys. Lett. 86(22), 222108 (2005).
[Crossref]

J. Li, K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Band-edge photoluminescence of AlN epilayers,” Appl. Phys. Lett. 81(18), 3365 (2002).
[Crossref]

Johnson, P. D.

T. Valla, P. D. Johnson, S. S. Dhesi, K. E. Smith, D. Doppalapudi, T. D. Moustakas, and E. L. Shirley, “Unoccupied band structure of wurtzite GaN(0001),” Phys. Rev. B 59(7), 5003–5007 (1999).
[Crossref]

Kako, S.

S. Kako, C. Santori, K. Hoshino, S. Götzinger, Y. Yamamoto, and Y. Arakawa, “A gallium nitride single-photon source operating at 200 K,” Nat. Mater. 5(11), 887–892 (2006).
[Crossref] [PubMed]

Kandaswamy, P. K.

J. Verma, S. M. Islam, V. Protasenko, P. K. Kandaswamy, H. L. Xing, and D. Jena, “Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures,” Appl. Phys. Lett. 104(2), 021105 (2014).
[Crossref]

Kang, J.

W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
[PubMed]

Kawamura, F.

A. N. Hattori, F. Kawamura, M. Yoshimura, Y. Kitaoka, Y. Mori, K. Hattori, H. Daimon, and K. Endo, “Chemical etchant dependence of surface structure and morphology on GaN(0001) substrates,” Surf. Sci. 604(15–16), 1247–1253 (2010).
[Crossref]

Kawasaki, K.

K. Kawasaki, D. Yamazaki, A. Kinoshita, H. Hirayama, K. Tsutsui, and Y. Aoyagi, “GaN quantum-dot formation by self-assembling droplet epitaxy and application to single-electron transistors,” Appl. Phys. Lett. 79(14), 2243–2245 (2001).
[Crossref]

Kinoshita, A.

K. Kawasaki, D. Yamazaki, A. Kinoshita, H. Hirayama, K. Tsutsui, and Y. Aoyagi, “GaN quantum-dot formation by self-assembling droplet epitaxy and application to single-electron transistors,” Appl. Phys. Lett. 79(14), 2243–2245 (2001).
[Crossref]

Kitaoka, Y.

A. N. Hattori, F. Kawamura, M. Yoshimura, Y. Kitaoka, Y. Mori, K. Hattori, H. Daimon, and K. Endo, “Chemical etchant dependence of surface structure and morphology on GaN(0001) substrates,” Surf. Sci. 604(15–16), 1247–1253 (2010).
[Crossref]

Kondo, T.

T. Kondo, K. Saitoh, Y. Yamamoto, T. Maruyama, and S. Naritsuka, “Fabrication of GaN dot structures on Si substrates by droplet epitaxy,” Physica Status Solidi a-Applications and Materials Science. 203(7), 1700–1703 (2006).
[Crossref]

Kuo, H. C.

W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
[PubMed]

Lefebvre, D.

T. Huault, J. Brault, F. Natali, B. Damilano, D. Lefebvre, L. Nguyen, M. Leroux, and J. Massies, “Blue-light emission from GaN/Al[sub 0.5]Ga[sub 0.5]N quantum dots,” Appl. Phys. Lett. 92(5), 051911 (2008).
[Crossref]

Leroux, M.

T. Huault, J. Brault, F. Natali, B. Damilano, D. Lefebvre, L. Nguyen, M. Leroux, and J. Massies, “Blue-light emission from GaN/Al[sub 0.5]Ga[sub 0.5]N quantum dots,” Appl. Phys. Lett. 92(5), 051911 (2008).
[Crossref]

Li, J.

W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
[PubMed]

J. Li, K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Band-edge photoluminescence of AlN epilayers,” Appl. Phys. Lett. 81(18), 3365 (2002).
[Crossref]

Li, S.

W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
[PubMed]

X. Hui, J. Zhang, S. Li, H. Wang, Y. Fang, J. Dai, and C. Chen, “Fabrication of GaN nanodots via GaN thermal decomposition in H2 atmosphere,” J. Vac. Sci. Technol. B 31(5), 050607 (2013).
[Crossref]

Li, S. L.

H. Wang, S. L. Li, H. Xiong, Z. H. Wu, J. N. Dai, Y. Tian, Y. Y. Fang, and C. Q. Chen, “The effect of AlN nucleation temperature on the growth of AlN films via metalorganic chemical vapor deposition,” J. Electron. Mater. 41(3), 466–470 (2012).
[Crossref]

Lin, J. Y.

A. Sedhain, J. Y. Lin, and H. X. Jiang, “Nature of optical transitions involving cation vacancies and complexes in AlN and AlGaN,” Appl. Phys. Lett. 100(22), 221107 (2012).
[Crossref]

A. Sedhain, L. Du, J. H. Edgar, J. Y. Lin, and H. X. Jiang, “The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates,” Appl. Phys. Lett. 95(26), 262104 (2009).
[Crossref]

K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Deep impurity transitions involving cation vacancies and complexes in AlGaN alloys,” Appl. Phys. Lett. 86(22), 222108 (2005).
[Crossref]

J. Li, K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Band-edge photoluminescence of AlN epilayers,” Appl. Phys. Lett. 81(18), 3365 (2002).
[Crossref]

Liu, D.

W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
[PubMed]

Lorenz, K.

M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010).
[Crossref]

Lu, T. C.

W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
[PubMed]

Luth, H.

R. K. Debnath, T. Stoica, A. Besmehn, K. Jeganathan, E. Sutter, R. Meijers, H. Luth, and R. Calarco, “Formation of GaN nanodots on Si (111) by droplet nitridation,” J. Cryst. Growth 311(13), 3389–3394 (2009).
[Crossref]

Magalhaes, S.

M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010).
[Crossref]

Martos, D.

M. Gherasimova, G. Cui, S. R. Jeon, Z. Ren, D. Martos, J. Han, Y. He, and A. V. Nurmikko, “Droplet heteroepitaxy of GaN quantum dots by metal-organic chemical vapor deposition,” Appl. Phys. Lett. 85(12), 2346–2348 (2004).
[Crossref]

Maruyama, T.

T. Kondo, K. Saitoh, Y. Yamamoto, T. Maruyama, and S. Naritsuka, “Fabrication of GaN dot structures on Si substrates by droplet epitaxy,” Physica Status Solidi a-Applications and Materials Science. 203(7), 1700–1703 (2006).
[Crossref]

Massies, J.

T. Huault, J. Brault, F. Natali, B. Damilano, D. Lefebvre, L. Nguyen, M. Leroux, and J. Massies, “Blue-light emission from GaN/Al[sub 0.5]Ga[sub 0.5]N quantum dots,” Appl. Phys. Lett. 92(5), 051911 (2008).
[Crossref]

J. Massies and J. P. Contour, “Substrate chemical etching prior to molecular-beam epitaxy: An x-ray photoelectron spectroscopy study of GaAs {001} surfaces etched by the H2SO4-H2O2-H2O solution,” J. Appl. Phys. 58(2), 806 (1985).
[Crossref]

Meijers, R.

R. K. Debnath, T. Stoica, A. Besmehn, K. Jeganathan, E. Sutter, R. Meijers, H. Luth, and R. Calarco, “Formation of GaN nanodots on Si (111) by droplet nitridation,” J. Cryst. Growth 311(13), 3389–3394 (2009).
[Crossref]

Meyler, B.

J. C. Zhang, B. Meyler, A. Vardi, G. Bahir, and J. Salzman, “Stranski–Krastanov growth of GaN quantum dots on AlN template by metalorganic chemical vapor deposition,” J. Appl. Phys. 104(4), 044307 (2008).
[Crossref]

Monteiro, T.

M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010).
[Crossref]

Mori, Y.

A. N. Hattori, F. Kawamura, M. Yoshimura, Y. Kitaoka, Y. Mori, K. Hattori, H. Daimon, and K. Endo, “Chemical etchant dependence of surface structure and morphology on GaN(0001) substrates,” Surf. Sci. 604(15–16), 1247–1253 (2010).
[Crossref]

Morimoto, Y.

Y. Morimoto, “Few Characteristics of Epitaxial GaN—Etching and Thermal Decomposition,” J. Electrochem. Soc. 121(10), 1383–1384 (1974).
[Crossref]

Moustakas, T. D.

T. Valla, P. D. Johnson, S. S. Dhesi, K. E. Smith, D. Doppalapudi, T. D. Moustakas, and E. L. Shirley, “Unoccupied band structure of wurtzite GaN(0001),” Phys. Rev. B 59(7), 5003–5007 (1999).
[Crossref]

S. S. Dhesi, C. B. Stagarescu, K. E. Smith, D. Doppalapudi, R. Singh, and T. D. Moustakas, “Surface and bulk electronic structure of thin-film wurtzite GaN,” Phys. Rev. B 56(16), 10271–10275 (1997).
[Crossref]

Nakarmi, M. L.

K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Deep impurity transitions involving cation vacancies and complexes in AlGaN alloys,” Appl. Phys. Lett. 86(22), 222108 (2005).
[Crossref]

J. Li, K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Band-edge photoluminescence of AlN epilayers,” Appl. Phys. Lett. 81(18), 3365 (2002).
[Crossref]

Nam, K. B.

K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Deep impurity transitions involving cation vacancies and complexes in AlGaN alloys,” Appl. Phys. Lett. 86(22), 222108 (2005).
[Crossref]

J. Li, K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Band-edge photoluminescence of AlN epilayers,” Appl. Phys. Lett. 81(18), 3365 (2002).
[Crossref]

Naritsuka, S.

T. Kondo, K. Saitoh, Y. Yamamoto, T. Maruyama, and S. Naritsuka, “Fabrication of GaN dot structures on Si substrates by droplet epitaxy,” Physica Status Solidi a-Applications and Materials Science. 203(7), 1700–1703 (2006).
[Crossref]

Natali, F.

T. Huault, J. Brault, F. Natali, B. Damilano, D. Lefebvre, L. Nguyen, M. Leroux, and J. Massies, “Blue-light emission from GaN/Al[sub 0.5]Ga[sub 0.5]N quantum dots,” Appl. Phys. Lett. 92(5), 051911 (2008).
[Crossref]

Neves, A. J.

M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010).
[Crossref]

Nguyen, L.

T. Huault, J. Brault, F. Natali, B. Damilano, D. Lefebvre, L. Nguyen, M. Leroux, and J. Massies, “Blue-light emission from GaN/Al[sub 0.5]Ga[sub 0.5]N quantum dots,” Appl. Phys. Lett. 92(5), 051911 (2008).
[Crossref]

Normand, P.

P. Dimitrakis, P. Normand, V. Ioannou-Sougleridis, C. Bonafos, S. Schamm-Chardon, G. BenAssayag, and E. Iliopoulos, “Quantum dots for memory applications,” Phys. Status Solidi210(8), 1490–1504 (2013) (a).
[Crossref]

Nurmikko, A. V.

M. Gherasimova, G. Cui, S. R. Jeon, Z. Ren, D. Martos, J. Han, Y. He, and A. V. Nurmikko, “Droplet heteroepitaxy of GaN quantum dots by metal-organic chemical vapor deposition,” Appl. Phys. Lett. 85(12), 2346–2348 (2004).
[Crossref]

Okuno-Vila, H.

M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010).
[Crossref]

Pelekanos, N. T.

F. Widmann, J. Simon, B. Daudin, G. Feuillet, J. L. Rouviere, N. T. Pelekanos, and G. Fishman, “Blue-light emission from GaN self-assembled quantum dots due to giant piezoelectric effect,” Phys. Rev. B 58(24), 15989 (1998).
[Crossref]

Peres, M.

M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010).
[Crossref]

Ponce, F. A.

C. W. Hu, A. Bell, F. A. Ponce, D. J. Smith, and I. S. T. Tsong, “Growth of self-assembled GaN quantum dots via the vapor–liquid–solid mechanism,” Appl. Phys. Lett. 81(17), 3236 (2002).
[Crossref]

Protasenko, V.

J. Verma, S. M. Islam, V. Protasenko, P. K. Kandaswamy, H. L. Xing, and D. Jena, “Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures,” Appl. Phys. Lett. 104(2), 021105 (2014).
[Crossref]

Raab, A.

A. Raab and G. Springholz, “Oswald ripening and shape transitions of self-assembled PbSe quantum dots on PbTe (111) during annealing,” Appl. Phys. Lett. 77(19), 2991–2993 (2000).
[Crossref]

Razi, S.

Ren, Z.

M. Gherasimova, G. Cui, S. R. Jeon, Z. Ren, D. Martos, J. Han, Y. He, and A. V. Nurmikko, “Droplet heteroepitaxy of GaN quantum dots by metal-organic chemical vapor deposition,” Appl. Phys. Lett. 85(12), 2346–2348 (2004).
[Crossref]

Rouviere, J. L.

F. Widmann, J. Simon, B. Daudin, G. Feuillet, J. L. Rouviere, N. T. Pelekanos, and G. Fishman, “Blue-light emission from GaN self-assembled quantum dots due to giant piezoelectric effect,” Phys. Rev. B 58(24), 15989 (1998).
[Crossref]

Saitoh, K.

T. Kondo, K. Saitoh, Y. Yamamoto, T. Maruyama, and S. Naritsuka, “Fabrication of GaN dot structures on Si substrates by droplet epitaxy,” Physica Status Solidi a-Applications and Materials Science. 203(7), 1700–1703 (2006).
[Crossref]

Salzman, J.

J. C. Zhang, B. Meyler, A. Vardi, G. Bahir, and J. Salzman, “Stranski–Krastanov growth of GaN quantum dots on AlN template by metalorganic chemical vapor deposition,” J. Appl. Phys. 104(4), 044307 (2008).
[Crossref]

Santori, C.

S. Kako, C. Santori, K. Hoshino, S. Götzinger, Y. Yamamoto, and Y. Arakawa, “A gallium nitride single-photon source operating at 200 K,” Nat. Mater. 5(11), 887–892 (2006).
[Crossref] [PubMed]

Schamm-Chardon, S.

P. Dimitrakis, P. Normand, V. Ioannou-Sougleridis, C. Bonafos, S. Schamm-Chardon, G. BenAssayag, and E. Iliopoulos, “Quantum dots for memory applications,” Phys. Status Solidi210(8), 1490–1504 (2013) (a).
[Crossref]

Sedhain, A.

A. Sedhain, J. Y. Lin, and H. X. Jiang, “Nature of optical transitions involving cation vacancies and complexes in AlN and AlGaN,” Appl. Phys. Lett. 100(22), 221107 (2012).
[Crossref]

A. Sedhain, L. Du, J. H. Edgar, J. Y. Lin, and H. X. Jiang, “The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates,” Appl. Phys. Lett. 95(26), 262104 (2009).
[Crossref]

Shirley, E. L.

T. Valla, P. D. Johnson, S. S. Dhesi, K. E. Smith, D. Doppalapudi, T. D. Moustakas, and E. L. Shirley, “Unoccupied band structure of wurtzite GaN(0001),” Phys. Rev. B 59(7), 5003–5007 (1999).
[Crossref]

Simon, J.

F. Widmann, J. Simon, B. Daudin, G. Feuillet, J. L. Rouviere, N. T. Pelekanos, and G. Fishman, “Blue-light emission from GaN self-assembled quantum dots due to giant piezoelectric effect,” Phys. Rev. B 58(24), 15989 (1998).
[Crossref]

Singh, R.

S. S. Dhesi, C. B. Stagarescu, K. E. Smith, D. Doppalapudi, R. Singh, and T. D. Moustakas, “Surface and bulk electronic structure of thin-film wurtzite GaN,” Phys. Rev. B 56(16), 10271–10275 (1997).
[Crossref]

Smith, D. J.

C. W. Hu, A. Bell, F. A. Ponce, D. J. Smith, and I. S. T. Tsong, “Growth of self-assembled GaN quantum dots via the vapor–liquid–solid mechanism,” Appl. Phys. Lett. 81(17), 3236 (2002).
[Crossref]

Smith, K. E.

T. Valla, P. D. Johnson, S. S. Dhesi, K. E. Smith, D. Doppalapudi, T. D. Moustakas, and E. L. Shirley, “Unoccupied band structure of wurtzite GaN(0001),” Phys. Rev. B 59(7), 5003–5007 (1999).
[Crossref]

S. S. Dhesi, C. B. Stagarescu, K. E. Smith, D. Doppalapudi, R. Singh, and T. D. Moustakas, “Surface and bulk electronic structure of thin-film wurtzite GaN,” Phys. Rev. B 56(16), 10271–10275 (1997).
[Crossref]

Springholz, G.

A. Raab and G. Springholz, “Oswald ripening and shape transitions of self-assembled PbSe quantum dots on PbTe (111) during annealing,” Appl. Phys. Lett. 77(19), 2991–2993 (2000).
[Crossref]

Stagarescu, C. B.

S. S. Dhesi, C. B. Stagarescu, K. E. Smith, D. Doppalapudi, R. Singh, and T. D. Moustakas, “Surface and bulk electronic structure of thin-film wurtzite GaN,” Phys. Rev. B 56(16), 10271–10275 (1997).
[Crossref]

Stoica, T.

R. K. Debnath, T. Stoica, A. Besmehn, K. Jeganathan, E. Sutter, R. Meijers, H. Luth, and R. Calarco, “Formation of GaN nanodots on Si (111) by droplet nitridation,” J. Cryst. Growth 311(13), 3389–3394 (2009).
[Crossref]

Sutter, E.

R. K. Debnath, T. Stoica, A. Besmehn, K. Jeganathan, E. Sutter, R. Meijers, H. Luth, and R. Calarco, “Formation of GaN nanodots on Si (111) by droplet nitridation,” J. Cryst. Growth 311(13), 3389–3394 (2009).
[Crossref]

Sze, S. M.

J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013).
[Crossref]

Tian, Y.

H. Wang, S. L. Li, H. Xiong, Z. H. Wu, J. N. Dai, Y. Tian, Y. Y. Fang, and C. Q. Chen, “The effect of AlN nucleation temperature on the growth of AlN films via metalorganic chemical vapor deposition,” J. Electron. Mater. 41(3), 466–470 (2012).
[Crossref]

Tsai, M. J.

J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013).
[Crossref]

Tseng, H. C.

J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013).
[Crossref]

Tsong, I. S. T.

C. W. Hu, A. Bell, F. A. Ponce, D. J. Smith, and I. S. T. Tsong, “Growth of self-assembled GaN quantum dots via the vapor–liquid–solid mechanism,” Appl. Phys. Lett. 81(17), 3236 (2002).
[Crossref]

Tsutsui, K.

K. Kawasaki, D. Yamazaki, A. Kinoshita, H. Hirayama, K. Tsutsui, and Y. Aoyagi, “GaN quantum-dot formation by self-assembling droplet epitaxy and application to single-electron transistors,” Appl. Phys. Lett. 79(14), 2243–2245 (2001).
[Crossref]

Valla, T.

T. Valla, P. D. Johnson, S. S. Dhesi, K. E. Smith, D. Doppalapudi, T. D. Moustakas, and E. L. Shirley, “Unoccupied band structure of wurtzite GaN(0001),” Phys. Rev. B 59(7), 5003–5007 (1999).
[Crossref]

Vardi, A.

J. C. Zhang, B. Meyler, A. Vardi, G. Bahir, and J. Salzman, “Stranski–Krastanov growth of GaN quantum dots on AlN template by metalorganic chemical vapor deposition,” J. Appl. Phys. 104(4), 044307 (2008).
[Crossref]

Verma, J.

J. Verma, S. M. Islam, V. Protasenko, P. K. Kandaswamy, H. L. Xing, and D. Jena, “Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures,” Appl. Phys. Lett. 104(2), 021105 (2014).
[Crossref]

Wang, H.

X. Hui, J. Zhang, S. Li, H. Wang, Y. Fang, J. Dai, and C. Chen, “Fabrication of GaN nanodots via GaN thermal decomposition in H2 atmosphere,” J. Vac. Sci. Technol. B 31(5), 050607 (2013).
[Crossref]

H. Wang, S. L. Li, H. Xiong, Z. H. Wu, J. N. Dai, Y. Tian, Y. Y. Fang, and C. Q. Chen, “The effect of AlN nucleation temperature on the growth of AlN films via metalorganic chemical vapor deposition,” J. Electron. Mater. 41(3), 466–470 (2012).
[Crossref]

Widmann, F.

F. Widmann, J. Simon, B. Daudin, G. Feuillet, J. L. Rouviere, N. T. Pelekanos, and G. Fishman, “Blue-light emission from GaN self-assembled quantum dots due to giant piezoelectric effect,” Phys. Rev. B 58(24), 15989 (1998).
[Crossref]

Wu, Z. H.

H. Wang, S. L. Li, H. Xiong, Z. H. Wu, J. N. Dai, Y. Tian, Y. Y. Fang, and C. Q. Chen, “The effect of AlN nucleation temperature on the growth of AlN films via metalorganic chemical vapor deposition,” J. Electron. Mater. 41(3), 466–470 (2012).
[Crossref]

Xing, H. L.

J. Verma, S. M. Islam, V. Protasenko, P. K. Kandaswamy, H. L. Xing, and D. Jena, “Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures,” Appl. Phys. Lett. 104(2), 021105 (2014).
[Crossref]

Xiong, H.

H. Wang, S. L. Li, H. Xiong, Z. H. Wu, J. N. Dai, Y. Tian, Y. Y. Fang, and C. Q. Chen, “The effect of AlN nucleation temperature on the growth of AlN films via metalorganic chemical vapor deposition,” J. Electron. Mater. 41(3), 466–470 (2012).
[Crossref]

Yamamoto, Y.

S. Kako, C. Santori, K. Hoshino, S. Götzinger, Y. Yamamoto, and Y. Arakawa, “A gallium nitride single-photon source operating at 200 K,” Nat. Mater. 5(11), 887–892 (2006).
[Crossref] [PubMed]

T. Kondo, K. Saitoh, Y. Yamamoto, T. Maruyama, and S. Naritsuka, “Fabrication of GaN dot structures on Si substrates by droplet epitaxy,” Physica Status Solidi a-Applications and Materials Science. 203(7), 1700–1703 (2006).
[Crossref]

Yamazaki, D.

K. Kawasaki, D. Yamazaki, A. Kinoshita, H. Hirayama, K. Tsutsui, and Y. Aoyagi, “GaN quantum-dot formation by self-assembling droplet epitaxy and application to single-electron transistors,” Appl. Phys. Lett. 79(14), 2243–2245 (2001).
[Crossref]

Yang, J. B.

J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013).
[Crossref]

Yang, P. C.

J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013).
[Crossref]

Yang, W.

W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
[PubMed]

Yang, X.

W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
[PubMed]

Yoshimura, M.

A. N. Hattori, F. Kawamura, M. Yoshimura, Y. Kitaoka, Y. Mori, K. Hattori, H. Daimon, and K. Endo, “Chemical etchant dependence of surface structure and morphology on GaN(0001) substrates,” Surf. Sci. 604(15–16), 1247–1253 (2010).
[Crossref]

Zhang, J.

X. Hui, J. Zhang, S. Li, H. Wang, Y. Fang, J. Dai, and C. Chen, “Fabrication of GaN nanodots via GaN thermal decomposition in H2 atmosphere,” J. Vac. Sci. Technol. B 31(5), 050607 (2013).
[Crossref]

Zhang, J. C.

J. C. Zhang, B. Meyler, A. Vardi, G. Bahir, and J. Salzman, “Stranski–Krastanov growth of GaN quantum dots on AlN template by metalorganic chemical vapor deposition,” J. Appl. Phys. 104(4), 044307 (2008).
[Crossref]

Zhang, Y.

W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
[PubMed]

Appl. Phys. Lett. (10)

J. Verma, S. M. Islam, V. Protasenko, P. K. Kandaswamy, H. L. Xing, and D. Jena, “Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures,” Appl. Phys. Lett. 104(2), 021105 (2014).
[Crossref]

K. Kawasaki, D. Yamazaki, A. Kinoshita, H. Hirayama, K. Tsutsui, and Y. Aoyagi, “GaN quantum-dot formation by self-assembling droplet epitaxy and application to single-electron transistors,” Appl. Phys. Lett. 79(14), 2243–2245 (2001).
[Crossref]

T. Huault, J. Brault, F. Natali, B. Damilano, D. Lefebvre, L. Nguyen, M. Leroux, and J. Massies, “Blue-light emission from GaN/Al[sub 0.5]Ga[sub 0.5]N quantum dots,” Appl. Phys. Lett. 92(5), 051911 (2008).
[Crossref]

C. W. Hu, A. Bell, F. A. Ponce, D. J. Smith, and I. S. T. Tsong, “Growth of self-assembled GaN quantum dots via the vapor–liquid–solid mechanism,” Appl. Phys. Lett. 81(17), 3236 (2002).
[Crossref]

M. Gherasimova, G. Cui, S. R. Jeon, Z. Ren, D. Martos, J. Han, Y. He, and A. V. Nurmikko, “Droplet heteroepitaxy of GaN quantum dots by metal-organic chemical vapor deposition,” Appl. Phys. Lett. 85(12), 2346–2348 (2004).
[Crossref]

A. Raab and G. Springholz, “Oswald ripening and shape transitions of self-assembled PbSe quantum dots on PbTe (111) during annealing,” Appl. Phys. Lett. 77(19), 2991–2993 (2000).
[Crossref]

J. Li, K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Band-edge photoluminescence of AlN epilayers,” Appl. Phys. Lett. 81(18), 3365 (2002).
[Crossref]

A. Sedhain, L. Du, J. H. Edgar, J. Y. Lin, and H. X. Jiang, “The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates,” Appl. Phys. Lett. 95(26), 262104 (2009).
[Crossref]

A. Sedhain, J. Y. Lin, and H. X. Jiang, “Nature of optical transitions involving cation vacancies and complexes in AlN and AlGaN,” Appl. Phys. Lett. 100(22), 221107 (2012).
[Crossref]

K. B. Nam, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Deep impurity transitions involving cation vacancies and complexes in AlGaN alloys,” Appl. Phys. Lett. 86(22), 222108 (2005).
[Crossref]

J. Appl. Phys. (2)

J. Massies and J. P. Contour, “Substrate chemical etching prior to molecular-beam epitaxy: An x-ray photoelectron spectroscopy study of GaAs {001} surfaces etched by the H2SO4-H2O2-H2O solution,” J. Appl. Phys. 58(2), 806 (1985).
[Crossref]

J. C. Zhang, B. Meyler, A. Vardi, G. Bahir, and J. Salzman, “Stranski–Krastanov growth of GaN quantum dots on AlN template by metalorganic chemical vapor deposition,” J. Appl. Phys. 104(4), 044307 (2008).
[Crossref]

J. Cryst. Growth (1)

R. K. Debnath, T. Stoica, A. Besmehn, K. Jeganathan, E. Sutter, R. Meijers, H. Luth, and R. Calarco, “Formation of GaN nanodots on Si (111) by droplet nitridation,” J. Cryst. Growth 311(13), 3389–3394 (2009).
[Crossref]

J. Electrochem. Soc. (1)

Y. Morimoto, “Few Characteristics of Epitaxial GaN—Etching and Thermal Decomposition,” J. Electrochem. Soc. 121(10), 1383–1384 (1974).
[Crossref]

J. Electron. Mater. (1)

H. Wang, S. L. Li, H. Xiong, Z. H. Wu, J. N. Dai, Y. Tian, Y. Y. Fang, and C. Q. Chen, “The effect of AlN nucleation temperature on the growth of AlN films via metalorganic chemical vapor deposition,” J. Electron. Mater. 41(3), 466–470 (2012).
[Crossref]

J. Vac. Sci. Technol. B (1)

X. Hui, J. Zhang, S. Li, H. Wang, Y. Fang, J. Dai, and C. Chen, “Fabrication of GaN nanodots via GaN thermal decomposition in H2 atmosphere,” J. Vac. Sci. Technol. B 31(5), 050607 (2013).
[Crossref]

Nat. Mater. (1)

S. Kako, C. Santori, K. Hoshino, S. Götzinger, Y. Yamamoto, and Y. Arakawa, “A gallium nitride single-photon source operating at 200 K,” Nat. Mater. 5(11), 887–892 (2006).
[Crossref] [PubMed]

Opt. Express (1)

Phys. Rev. B (3)

F. Widmann, J. Simon, B. Daudin, G. Feuillet, J. L. Rouviere, N. T. Pelekanos, and G. Fishman, “Blue-light emission from GaN self-assembled quantum dots due to giant piezoelectric effect,” Phys. Rev. B 58(24), 15989 (1998).
[Crossref]

S. S. Dhesi, C. B. Stagarescu, K. E. Smith, D. Doppalapudi, R. Singh, and T. D. Moustakas, “Surface and bulk electronic structure of thin-film wurtzite GaN,” Phys. Rev. B 56(16), 10271–10275 (1997).
[Crossref]

T. Valla, P. D. Johnson, S. S. Dhesi, K. E. Smith, D. Doppalapudi, T. D. Moustakas, and E. L. Shirley, “Unoccupied band structure of wurtzite GaN(0001),” Phys. Rev. B 59(7), 5003–5007 (1999).
[Crossref]

Phys. Status Solidi, B Basic Res. (1)

M. Peres, A. J. Neves, T. Monteiro, S. Magalhaes, E. Alves, K. Lorenz, H. Okuno-Vila, V. Fellmann, C. Bougerol, and B. Daudin, “Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots,” Phys. Status Solidi, B Basic Res. 247(7), 1675–1678 (2010).
[Crossref]

Physica Status Solidi a-Applications and Materials Science. (1)

T. Kondo, K. Saitoh, Y. Yamamoto, T. Maruyama, and S. Naritsuka, “Fabrication of GaN dot structures on Si substrates by droplet epitaxy,” Physica Status Solidi a-Applications and Materials Science. 203(7), 1700–1703 (2006).
[Crossref]

Sci Rep (1)

W. Yang, J. Li, Y. Zhang, P. K. Huang, T. C. Lu, H. C. Kuo, S. Li, X. Yang, H. Chen, D. Liu, and J. Kang, “High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability,” Sci Rep 4(5), 5166 (2014).
[PubMed]

Surf. Sci. (1)

A. N. Hattori, F. Kawamura, M. Yoshimura, Y. Kitaoka, Y. Mori, K. Hattori, H. Daimon, and K. Endo, “Chemical etchant dependence of surface structure and morphology on GaN(0001) substrates,” Surf. Sci. 604(15–16), 1247–1253 (2010).
[Crossref]

Thin Solid Films (1)

J. B. Yang, T. C. Chang, J. J. Huang, S. C. Chen, P. C. Yang, Y. T. Chen, H. C. Tseng, S. M. Sze, A. K. Chu, and M. J. Tsai, “Resistive switching characteristics of gallium oxide for nonvolatile memory application,” Thin Solid Films 529, 200–204 (2013).
[Crossref]

Other (2)

P. Dimitrakis, P. Normand, V. Ioannou-Sougleridis, C. Bonafos, S. Schamm-Chardon, G. BenAssayag, and E. Iliopoulos, “Quantum dots for memory applications,” Phys. Status Solidi210(8), 1490–1504 (2013) (a).
[Crossref]

K. Hoshino and Y. Arakawa, “Effect of thermal treatment on structure of GaN self-assembled quantum dots grown by MOCVD,” 2nd International Conference on Semiconductor Quantum Dots0(4), 1101–1104 (2003).
[Crossref]

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Figures (6)

Fig. 1
Fig. 1 AFM images of GaN dots or Ga metallic dots without annealing in scan area of 2 × 2 um2, the height scale is 20 nm.
Fig. 2
Fig. 2 AFM images of GaN QDs annealed under NH3/H2 ambience at 700 °C (a); 750 °C (b); 800 °C (c); 850 °C (d), and GaN QDs annealed under NH3/N2 ambience at 750 °C (e); 800 °C (f); 850 °C (g); 900 °C (h) in scan area of 2 × 2 um2, the height scale for all the images is 20 nm.
Fig. 3
Fig. 3 XPS survey spectra of samples annealed at 900 °C and 950 °C under H2/NH3 ambient.
Fig. 4
Fig. 4 XPS spectra from Ga 3d core levels of the GaN QDs annealed at different temperature (a) in H2 ambient, (b) in N2 ambient. Dashed lines correspond to fitted curves for each bond.
Fig. 5
Fig. 5 Room temperature PL spectra of surface GaN QDs.
Fig. 6
Fig. 6 A schematic energy diagram about the band alignment of surface GaN/AlN QDs

Tables (2)

Tables Icon

Table 1 The quantitative statistics of morphologies

Tables Icon

Table 2 The proportion of Ga-O, Ga-N and Ga metal

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