Abstract

Vertically aligned InGaN/GaN nanorod light emitting diode (LED) arrays were created from planar LED structures using a new top-down fabrication technique consisting of a plasma etch followed by an anisotropic wet etch. The wet etch results in straight, smooth, well-faceted nanorods with controllable diameters and removes the plasma etch damage. 94% of the nanorod LEDs are dislocation-free and a reduced quantum confined Stark effect is observed due to reduced piezoelectric fields. Despite these advantages, the IQE of the nanorod LEDs measured by photoluminescence is comparable to the planar LED, perhaps due to inefficient thermal transport and enhanced nonradiative surface recombination.

©2011 Optical Society of America

1. Introduction

Improving the performance of Group-III nitride (AlGaInN) based light emitting diodes (LEDs) has been the intense focus of research and development efforts worldwide. While current LEDs are based on planar thin-film architectures, vertically aligned nanorods (also called nanowires or nanocolumns) are currently being explored as an alternative architecture. Several advantages of nanorod-based LEDs have been recently reported. For example, nanorod-based LEDs enhance light extraction due to light scattering, optical mode elimination, and efficient light out-coupling [1]. Strain-relaxed, bottom-up nanorod growth also enables high crystalline quality with significantly reduced threading dislocation densities [2]. Higher indium compositions, which are desired for longer green-red wavelength emission, can be achieved with nanowires because of their compliance properties and strain relief mechanisms [3,4]. Variability in the emission wavelengths across nanowires within an ensemble can lead to phosphor-free “white” LEDs [5,6]. Additionally, suppressed quantum confined Stark effect (QCSE) [7] and reduced droop in InGaN/GaN nanowires [8] have also been reported.

Growth of InGaN/GaN-based nanorod LEDs by bottom-up methods, including hydride vapor phase epitaxy [9] and molecular beam epitaxy [5,8,10], have been demonstrated. However, relatively low growth temperatures and low V to III ratio are commonly used to promote anisotropic one dimensional crystal growth. Metal catalyzed-grown nanowires also require narrow growth conditions which involves lower than optimal growth temperatures [11]. These growth conditions may introduce higher impurities and point defect densities [12,13] than the conditions used for creating commercial-quality planar LEDs and provide less flexibility for adjusting growth parameters to optimize doping concentrations and other desired material properties.

In contrast, nanorods fabricated by top-down methods are etched from planar thin film LED structures grown under optimized growth conditions, obviating these disadvantages. Tapered, non-faceted InGaN-based nanorod LEDs have been previously demonstrated by plasma etching planar LED structures [7,14]. However, the top-down plasma etching leads to damaged, rough, and non-faceted sidewalls with defects, and leakage currents that limits performance [7]. Here we demonstrate a top-down strategy for creating nanorod LEDs from planar LED wafers using a two-step process that adds a selective anisotropic wet etch after the initial plasma etch to remove the dry etch damage while enabling nanorods with straight and smooth faceted sidewalls and controllable diameters independent of pitch. The nanorod LEDs created by this two-step process show potential for enhancing the internal quantum efficiency (IQE) of InGaN/GaN multi-quantum wells (MQWs).

2. Experimental procedures

For the nanorod LED fabrication, a prototypical InGaN/GaN MQW planar LED structures were first grown on c-plane sapphire in a Veeco D-125 metal organic chemical vapor deposition reactor. The MQW structure consists of a 2.5 µm thick Si-doped n-type GaN layer grown at 1050°C followed by a 5-period MQW comprised of 2.5 nm thick In0.13Ga0.87N wells and 7.2 nm thick GaN barriers grown at 770 °C. In addition, a 22 nm thick p-Al0.2Ga0.8N layer and a 200 nm thick p-type GaN contact layer were grown sequentially after the MQWs. After the growth, a close-packed monolayer of 1 µm diameter silica spheres was then self-assembled on the GaN surface in a Langmuir-Blodgett trough as previously reported [15]. The silica colloid monolayer functions as a mask in subsequent inductively coupled plasma etches. Previously plasma etching has been used to create GaN nanorods [16] and GaN-based LED nanorods [7,14] using various etch masks. In this work we follow the plasma etch step with a selective KOH-based wet etch (AZ400K photoresist developer, AZ Electronic Materials USA Corp) [17,18]. With this etchant, the top Ga-polar c-plane surface has a near-zero etch rate while the {10-10} m-plane sidewalls have a relatively fast etch rate compared to the other planes. As a result, the height of nanorod LEDs remains constant and the tapered sidewalls are eventually replaced with six straight and smooth m-plane sidewalls. The nanorod LED array and the original planar LED control sample were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), transmission electron microscopy (TEM), and temperature (4K-298K) and pump power dependent photoluminescence (PL).

3. Results and discussion

Figure 1(a) shows a SEM image of a planar LED structure covered with a hexagonal close-packed monolayer of silica spheres. After plasma etching, truncated cone-shaped nanorods are formed (Fig. 1(b)). After, the anisotropic wet etch using AZ400K, nanorods with straight and smooth sidewalls are produced, as seen in Fig. 1(c). The n-type GaN etches more quickly than the p-type GaN, leading to “flashlight” or “golf-tee” shaped nanorod LEDs, as shown in Figs. 1(c) and 1(d). The mechanism responsible for the faster n-type etch rate is not currently known. Previously, p-type GaN has been reported to be resistant to photoelectrochemical etching, as photogenerated holes needed for oxidation of the surface are swept away from the depletion region near the surface into the bulk [19]. While our etch process is neither photo- nor electrically assisted, it is possible that the presence of holes at the surface or the different surface potential between n-type and p-type GaN [20] is responsible for the difference in wet etch rates observed here.

 

Fig. 1 SEM images of (a) a planar LED wafer covered with a monolayer of self-assembled silica spheres, (b) tapered nanorod LEDs created by plasma etch, and (c) “flashlight” shaped nanorod LEDs array following wet etch. (d) A STEM image of nanorod “flashlight” LEDs showing the position of the InGaN MQWs (bright stripes).

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In addition to allowing for control of the nanowire geometry, the wet etch step also serves to remove damage in the nanorod sidewalls caused by high energy ion bombardment during the plasma etch. This ion damage was reported to cause a Ga-rich surface in GaN films [21] with efficient nonradiative recombination centers [22] and a deterioration in PL intensity. Moreover, vacancies may form near the surface region and trap or scatter carriers leading to high static resistance and reduced carrier mobility [23]. Room-temperature PL (266 nm pump) showed the appearance of strong defect-related yellow luminescence from GaN nanorods etched from a GaN epilayer after the plasma etch, as shown in Fig. 2 . However, after subsequent wet etching the nanorod samples in AZ400K, the yellow luminescence intensity was significantly reduced to a level similar to that of the planar GaN thin film prior to the plasma etch. This result unambiguously shows the wet etch step successfully removes the damage caused by the plasma etch. The slight redshift of the band edge luminescence in the nanorod samples compared to the planar sample may be a result of laser-induced heating effects caused by poorer thermal transport properties [24]. We note that drawing conclusions based on comparing the absolute band edge and yellow intensities of the samples is difficult, as various factors can impact the PL intensities. For example, the nanorod samples likely experience enhanced pump laser absorption and higher light extraction efficiencies, but have only a small fraction of the original volume of the planar sample. However, the relative contribution of each of these factors cannot be deconvolved.

 

Fig. 2 PL spectra of GaN thin film (solid black) and GaN nanorods after plasma etch (dashed-dotted red) and subsequent wet etch (dotted blue).

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Bright-field TEM imaging was performed to study the dislocation morphology of the nanorods under multi-beam conditions to reveal dislocations with different Burger’s vectors. Typical TEM images are shown in Fig. 3 . TEM imaging of 100 randomly sampled nanorods reveals that 94 nanorods are free of threading dislocations. The threading dislocation density in the initial planar LEDs epilayers before etching was measured to be ~5 dislocations/µm2 (5 × 108 cm−2), which is typical for commercial quality LEDs. Thus, for nanorod diameters ~150 nm (with cross-sectional area ~0.02 µm−2), the average number of dislocations per nanorod is ~0.1. In reality, each nanorod either has one or more dislocations or is dislocation free. Therefore, unlike bulk LEDs, which have a distribution of dislocations throughout, a nanorod LED array is comprised of individual LED elements which are largely dislocation-free. This nearly dislocation-free nanorod architecture could, compared to planar LEDs, have lower leakage currents, less non-radiative recombination, higher IQE, and higher lifespans. This result also shows that nanorods formed by top-down etching can be nearly dislocation free even though they are not grown strain-relaxed like bottom-up nanowires.

 

Fig. 3 TEM images of etched nanorod LED structures. A dislocation is indicated by the arrow in (a).

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The room temperature PL spectra of the nanorod LED InGaN MQWs excited by a 413.1 nm Krypton ion laser are compared to the planar LED in Figs. 4(a) and 4(b). The PL spectra peak positions were determined using Gaussian fit and plotted as a function of pumping power in Fig. 4(c). For both structures there is a blue shift in the emission wavelength with pump power (carrier injection) caused by free carrier screening of the QCSE. The QCSE results from spontaneous polarization field caused by low symmetry of c-plane III-nitride crystal structure and piezoelectric polarization field caused by lattice mismatch strain at InGaN/GaN interfaces. These internal fields may lower the IQE by reducing carrier wavefunction overlap. By comparing (0002) ω/2θ XRD scans taken before and after nanorod etching and by applying an appropriate elasticity theory analysis, we estimate that the coherency strain of the individual InGaN QWs was reduced by 16 ± 4% because of the elastic response enabled by nanorod formation. A further comparison of our planar sample’s emission at low power (445 nm) to the bulk bandgap [25] of In0.13Ga0.87N (426 nm) indicates a QW Stark shift in the planar sample of ~19 nm. Assuming that the change in strain linearly alters the piezoelectrically dominated Stark shift, we estimate a ~3.0 nm blue shift (0.16 x 19 nm) for the nanorod QW emission relative to that of the planar sample. In Fig. 4(c), we see a measured blue shift of ~4 nm (from about 445 to 441 nm for the planar vs. nanorod sample) at low power, in approximate agreement with our estimates and in support of partial QW strain relaxation due to wire formation. A smaller maximum blue shift of ~2 nm in the nanorod InGaN peak position as the pumping power is increased from 0 to 100 mW compared to the 6 nm shift observed in the planar LED is also evidence for reduced QCSE in the nanorod LEDs, consistent with a previous report [7].

 

Fig. 4 MQW PL of (a) nanorod LEDs and (b) planar LED. (c) MQW PL peak position plotted as a function of pump power for planar LEDs and nanorod LEDs.

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Due to the reduction in the piezoelectric polarization fields and relative lack of dislocations, the internal quantum efficiency of the nanorod LEDs might be expected to improve compared to the planar LED. Thus, the IQE (Fig. 5 ) of the nanorod and planar LEDs were measured by comparing their integrated PL intensity at room temperature with the maximum intensity measured at 4K and assuming unity IQE at 4K. Due to increased light scattering and light absorption, the nanorod LEDs likely experience a much higher equivalent pumping intensity (carrier concentration) at a given laser power compared to the planar sample, leading to the early peaking of the IQE. The IQE of the nanorod LEDs peaks at ~3 mW, (~24%), while the planar LED reaches its maximum IQE of ~27%, at a much higher pump power of ~55 mW. The peak IQEs are comparable so the formation of the nanowires did not compromise the IQE in an overly detrimental way. Additionally, it is possible that the decrease in IQE in the nanorod LEDs at relatively low pump powers may be caused by heating from the laser, due to the poor thermal transport properties of nanowires. This is supported by the red shift at higher pump powers observed in Fig. 4, consistent with a previous report where laser-induced produced redshifts in GaN nanowires during PL experiments [24].

 

Fig. 5 The IQE of the planar and nanorod LEDs plotted as a function of the optical pumping power.

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Despite the reduced piezoelectric polarization and their mostly dislocation-free nature, the measured InGaN MQW IQEs of the nanorod and planar LEDs are not significantly different. It is possible that the benefit of fewer dislocations and reduced piezoelectric polarization field is counterbalanced by heating effects or the higher surface to volume ratio, which could promote nonradiative carrier recombination [26] and space-charge-limited carrier transport [27]. Future surface passivation experiments, for example with an AlGaN shell [28,29], may shed further light into the role of surface states in these wet-etched structures.

4. Conclusion

In conclusion, we have developed a two-step top-down process for creating nanorod LED arrays from planar LED epitaxial structures. In contrast to previous work, this top-down technique combines the plasma etch with a subsequent anisotropic wet etch, which allows for removal of the plasma etch damage, while enabling straight nanorod sidewalls and control over the nanorod geometry. Despite the fact that the planar LEDs have a dislocation density of 5 µm−2, 94% of the nanorod LED structures are free of dislocations. The nanorod LEDs also show reduced QCSE compared to the planar LEDs due to reduced piezoelectric strain. The nanorod and planar LEDs were measured to have similar IQEs, perhaps due to heating effects and enhanced nonradiative recombination at the nanorod surfaces. These results suggest that these top-down nanorod LEDs have potential for higher-performance LEDs, although further work to investigate the role of thermal and surface effects is needed.

Acknowledgments

D. Koleske and S. Lee acknowledge support from Sandia’s Laboratory Directed Research and Development program. S. Fathololoumi and Z. Mi were funded by the Natural Sciences and Engineering Research Council of Canada. All other authors were supported by Sandia’s Solid-State-Lighting Science Energy Frontier Research Center, funded by the U.S. DOE Office of Basic Energy Sciences. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

References and links

1. C. H. Kuo, L. C. Chang, C. W. Kuo, and G. C. Chi, “Efficiency improvement of GaN-based light-emitting diode prepared on GaN nanorod template,” IEEE Photon. Technol. Lett. 22(4), 257–259 (2010). [CrossRef]  

2. S. D. Hersee, X. Y. Sun, and X. Wang, “The controlled growth of GaN nanowires,” Nano Lett. 6(8), 1808–1811 (2006). [CrossRef]   [PubMed]  

3. Q. M. Li and G. T. Wang, “Strain influenced indium composition distribution in GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 97(18), 181107 (2010). [CrossRef]  

4. T. Kuykendall, P. Ulrich, S. Aloni, and P. Yang, “Complete composition tunability of InGaN nanowires using a combinatorial approach,” Nat. Mater. 6(12), 951–956 (2007). [CrossRef]   [PubMed]  

5. H. W. Lin, Y. J. Lu, H. Y. Chen, H. M. Lee, and S. Gwo, “InGaN/GaN nanorod array white light-emitting diode,” Appl. Phys. Lett. 97(7), 073101 (2010). [CrossRef]  

6. H. Sekiguchi, K. Kishino, and A. Kikuchi, “Emission color control from blue to red with nanocolumn diameter of InGaN/GaN nanocolumn arrays grown on same substrate,” Appl. Phys. Lett. 96(23), 231104 (2010). [CrossRef]  

7. C. Y. Wang, L. Y. Chen, C. P. Chen, Y. W. Cheng, M. Y. Ke, M. Y. Hsieh, H. M. Wu, L. H. Peng, and J. Huang, “GaN nanorod light emitting diode arrays with a nearly constant electroluminescent peak wavelength,” Opt. Express 16(14), 10549–10556 (2008). [CrossRef]   [PubMed]  

8. H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011). [CrossRef]   [PubMed]  

9. H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004). [CrossRef]  

10. K. Kishino, A. Kikuchi, H. Sekiguchi, and S. Ishizawa, “InGaN/GaN nanocolumn LEDs emitting from blue to red,” Proc. SPIE 6473, 64730T (2007). [CrossRef]  

11. G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology 17(23), 5773–5780 (2006). [CrossRef]  

12. A. A. Talin, G. T. Wang, E. Lai, and R. J. Anderson, “Correlation of growth temperature, photoluminescence, and resistivity in GaN nanowires,” Appl. Phys. Lett. 92(9), 093105 (2008). [CrossRef]  

13. P. C. Upadhya, Q. M. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” Semicond. Sci. Technol. 25(2), 024017 (2010). [CrossRef]  

14. C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007). [CrossRef]  

15. Q. Li, J. J. Figiel, and G. T. Wang, “Dislocation density reduction in GaN by dislocation filtering through a self-assembled monolayer of silica microspheres,” Appl. Phys. Lett. 94(23), 231105 (2009). [CrossRef]  

16. Y. D. Wang, S. J. Chua, S. Tripathy, M. S. Sander, P. Chen, and C. G. Fonstad, “High optical quality GaN nanopillar arrays,” Appl. Phys. Lett. 86(7), 071917 (2005). [CrossRef]  

17. M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009). [CrossRef]  

18. D. A. Stocker, E. F. Schubert, and J. M. Redwing, “Crystallographic wet chemical etching of GaN,” Appl. Phys. Lett. 73(18), 2654–2656 (1998). [CrossRef]  

19. D. Zhuang and J. H. Edgar, “Wet etching of GaN, AIN, and SiC: a review,” Mater. Sci. Eng. Rep. 48(1), 1–46 (2005). [CrossRef]  

20. S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett. 93(21), 212107 (2008). [CrossRef]  

21. H. W. Choi, S. J. Chua, A. Raman, J. S. Pan, and A. T. S. Wee, “Plasma-induced damage to n-type GaN,” Appl. Phys. Lett. 77(12), 1795–1797 (2000). [CrossRef]  

22. Y. K. Byeun, K. S. Han, and S. C. Choi, “Influence on the growth temperature for one-dimesional GaN nanostructures by halide vapor-phase epitaxy,” J. Ceram. Process. Res. 6(3), 197–200 (2005).

23. S. J. Chua, H. W. Choi, J. Zhang, and P. Li, “Vacancy effects on plasma-induced damage to n-type GaN,” Phys. Rev. B 64(20), 205302 (2001). [CrossRef]  

24. H. W. Li, A. H. Chin, and M. K. Sunkara, “Direction-dependent homoepitaxial growth of GaN nanowires,” Adv. Mater. (Deerfield Beach Fla.) 18(2), 216–220 (2006). [CrossRef]  

25. J. Wu, W. Walukiewicz, K. M. Yu, J. W. Ager, E. E. Haller, H. Lu, and W. J. Schaff, “Small band gap bowing in In1-xGaxN alloys,” Appl. Phys. Lett. 80(25), 4741–4743 (2002). [CrossRef]  

26. E. Garnett and P. Yang, “Light trapping in silicon nanowire solar cells,” Nano Lett. 10(3), 1082–1087 (2010). [CrossRef]   [PubMed]  

27. A. A. Talin, F. Léonard, B. S. Swartzentruber, X. Wang, and S. D. Hersee, “Unusually strong space-charge-limited current in thin wires,” Phys. Rev. Lett. 101(7), 076802 (2008). [CrossRef]   [PubMed]  

28. A. Armstrong, Q. Li, Y. Lin, A. A. Talin, and G. T. Wang, “GaN nanowire surface state observed using deep level optical spectroscopy,” Appl. Phys. Lett. 96(16), 163106 (2010). [CrossRef]  

29. L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 98(13), 132104 (2011). [CrossRef]  

References

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  1. C. H. Kuo, L. C. Chang, C. W. Kuo, and G. C. Chi, “Efficiency improvement of GaN-based light-emitting diode prepared on GaN nanorod template,” IEEE Photon. Technol. Lett. 22(4), 257–259 (2010).
    [Crossref]
  2. S. D. Hersee, X. Y. Sun, and X. Wang, “The controlled growth of GaN nanowires,” Nano Lett. 6(8), 1808–1811 (2006).
    [Crossref] [PubMed]
  3. Q. M. Li and G. T. Wang, “Strain influenced indium composition distribution in GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 97(18), 181107 (2010).
    [Crossref]
  4. T. Kuykendall, P. Ulrich, S. Aloni, and P. Yang, “Complete composition tunability of InGaN nanowires using a combinatorial approach,” Nat. Mater. 6(12), 951–956 (2007).
    [Crossref] [PubMed]
  5. H. W. Lin, Y. J. Lu, H. Y. Chen, H. M. Lee, and S. Gwo, “InGaN/GaN nanorod array white light-emitting diode,” Appl. Phys. Lett. 97(7), 073101 (2010).
    [Crossref]
  6. H. Sekiguchi, K. Kishino, and A. Kikuchi, “Emission color control from blue to red with nanocolumn diameter of InGaN/GaN nanocolumn arrays grown on same substrate,” Appl. Phys. Lett. 96(23), 231104 (2010).
    [Crossref]
  7. C. Y. Wang, L. Y. Chen, C. P. Chen, Y. W. Cheng, M. Y. Ke, M. Y. Hsieh, H. M. Wu, L. H. Peng, and J. Huang, “GaN nanorod light emitting diode arrays with a nearly constant electroluminescent peak wavelength,” Opt. Express 16(14), 10549–10556 (2008).
    [Crossref] [PubMed]
  8. H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011).
    [Crossref] [PubMed]
  9. H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004).
    [Crossref]
  10. K. Kishino, A. Kikuchi, H. Sekiguchi, and S. Ishizawa, “InGaN/GaN nanocolumn LEDs emitting from blue to red,” Proc. SPIE 6473, 64730T (2007).
    [Crossref]
  11. G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology 17(23), 5773–5780 (2006).
    [Crossref]
  12. A. A. Talin, G. T. Wang, E. Lai, and R. J. Anderson, “Correlation of growth temperature, photoluminescence, and resistivity in GaN nanowires,” Appl. Phys. Lett. 92(9), 093105 (2008).
    [Crossref]
  13. P. C. Upadhya, Q. M. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” Semicond. Sci. Technol. 25(2), 024017 (2010).
    [Crossref]
  14. C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
    [Crossref]
  15. Q. Li, J. J. Figiel, and G. T. Wang, “Dislocation density reduction in GaN by dislocation filtering through a self-assembled monolayer of silica microspheres,” Appl. Phys. Lett. 94(23), 231105 (2009).
    [Crossref]
  16. Y. D. Wang, S. J. Chua, S. Tripathy, M. S. Sander, P. Chen, and C. G. Fonstad, “High optical quality GaN nanopillar arrays,” Appl. Phys. Lett. 86(7), 071917 (2005).
    [Crossref]
  17. M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009).
    [Crossref]
  18. D. A. Stocker, E. F. Schubert, and J. M. Redwing, “Crystallographic wet chemical etching of GaN,” Appl. Phys. Lett. 73(18), 2654–2656 (1998).
    [Crossref]
  19. D. Zhuang and J. H. Edgar, “Wet etching of GaN, AIN, and SiC: a review,” Mater. Sci. Eng. Rep. 48(1), 1–46 (2005).
    [Crossref]
  20. S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett. 93(21), 212107 (2008).
    [Crossref]
  21. H. W. Choi, S. J. Chua, A. Raman, J. S. Pan, and A. T. S. Wee, “Plasma-induced damage to n-type GaN,” Appl. Phys. Lett. 77(12), 1795–1797 (2000).
    [Crossref]
  22. Y. K. Byeun, K. S. Han, and S. C. Choi, “Influence on the growth temperature for one-dimesional GaN nanostructures by halide vapor-phase epitaxy,” J. Ceram. Process. Res. 6(3), 197–200 (2005).
  23. S. J. Chua, H. W. Choi, J. Zhang, and P. Li, “Vacancy effects on plasma-induced damage to n-type GaN,” Phys. Rev. B 64(20), 205302 (2001).
    [Crossref]
  24. H. W. Li, A. H. Chin, and M. K. Sunkara, “Direction-dependent homoepitaxial growth of GaN nanowires,” Adv. Mater. (Deerfield Beach Fla.) 18(2), 216–220 (2006).
    [Crossref]
  25. J. Wu, W. Walukiewicz, K. M. Yu, J. W. Ager, E. E. Haller, H. Lu, and W. J. Schaff, “Small band gap bowing in In1-xGaxN alloys,” Appl. Phys. Lett. 80(25), 4741–4743 (2002).
    [Crossref]
  26. E. Garnett and P. Yang, “Light trapping in silicon nanowire solar cells,” Nano Lett. 10(3), 1082–1087 (2010).
    [Crossref] [PubMed]
  27. A. A. Talin, F. Léonard, B. S. Swartzentruber, X. Wang, and S. D. Hersee, “Unusually strong space-charge-limited current in thin wires,” Phys. Rev. Lett. 101(7), 076802 (2008).
    [Crossref] [PubMed]
  28. A. Armstrong, Q. Li, Y. Lin, A. A. Talin, and G. T. Wang, “GaN nanowire surface state observed using deep level optical spectroscopy,” Appl. Phys. Lett. 96(16), 163106 (2010).
    [Crossref]
  29. L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 98(13), 132104 (2011).
    [Crossref]

2011 (2)

H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011).
[Crossref] [PubMed]

L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 98(13), 132104 (2011).
[Crossref]

2010 (7)

A. Armstrong, Q. Li, Y. Lin, A. A. Talin, and G. T. Wang, “GaN nanowire surface state observed using deep level optical spectroscopy,” Appl. Phys. Lett. 96(16), 163106 (2010).
[Crossref]

E. Garnett and P. Yang, “Light trapping in silicon nanowire solar cells,” Nano Lett. 10(3), 1082–1087 (2010).
[Crossref] [PubMed]

H. W. Lin, Y. J. Lu, H. Y. Chen, H. M. Lee, and S. Gwo, “InGaN/GaN nanorod array white light-emitting diode,” Appl. Phys. Lett. 97(7), 073101 (2010).
[Crossref]

H. Sekiguchi, K. Kishino, and A. Kikuchi, “Emission color control from blue to red with nanocolumn diameter of InGaN/GaN nanocolumn arrays grown on same substrate,” Appl. Phys. Lett. 96(23), 231104 (2010).
[Crossref]

C. H. Kuo, L. C. Chang, C. W. Kuo, and G. C. Chi, “Efficiency improvement of GaN-based light-emitting diode prepared on GaN nanorod template,” IEEE Photon. Technol. Lett. 22(4), 257–259 (2010).
[Crossref]

Q. M. Li and G. T. Wang, “Strain influenced indium composition distribution in GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 97(18), 181107 (2010).
[Crossref]

P. C. Upadhya, Q. M. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” Semicond. Sci. Technol. 25(2), 024017 (2010).
[Crossref]

2009 (2)

Q. Li, J. J. Figiel, and G. T. Wang, “Dislocation density reduction in GaN by dislocation filtering through a self-assembled monolayer of silica microspheres,” Appl. Phys. Lett. 94(23), 231105 (2009).
[Crossref]

M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009).
[Crossref]

2008 (4)

C. Y. Wang, L. Y. Chen, C. P. Chen, Y. W. Cheng, M. Y. Ke, M. Y. Hsieh, H. M. Wu, L. H. Peng, and J. Huang, “GaN nanorod light emitting diode arrays with a nearly constant electroluminescent peak wavelength,” Opt. Express 16(14), 10549–10556 (2008).
[Crossref] [PubMed]

A. A. Talin, F. Léonard, B. S. Swartzentruber, X. Wang, and S. D. Hersee, “Unusually strong space-charge-limited current in thin wires,” Phys. Rev. Lett. 101(7), 076802 (2008).
[Crossref] [PubMed]

A. A. Talin, G. T. Wang, E. Lai, and R. J. Anderson, “Correlation of growth temperature, photoluminescence, and resistivity in GaN nanowires,” Appl. Phys. Lett. 92(9), 093105 (2008).
[Crossref]

S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett. 93(21), 212107 (2008).
[Crossref]

2007 (3)

T. Kuykendall, P. Ulrich, S. Aloni, and P. Yang, “Complete composition tunability of InGaN nanowires using a combinatorial approach,” Nat. Mater. 6(12), 951–956 (2007).
[Crossref] [PubMed]

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
[Crossref]

K. Kishino, A. Kikuchi, H. Sekiguchi, and S. Ishizawa, “InGaN/GaN nanocolumn LEDs emitting from blue to red,” Proc. SPIE 6473, 64730T (2007).
[Crossref]

2006 (3)

G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology 17(23), 5773–5780 (2006).
[Crossref]

S. D. Hersee, X. Y. Sun, and X. Wang, “The controlled growth of GaN nanowires,” Nano Lett. 6(8), 1808–1811 (2006).
[Crossref] [PubMed]

H. W. Li, A. H. Chin, and M. K. Sunkara, “Direction-dependent homoepitaxial growth of GaN nanowires,” Adv. Mater. (Deerfield Beach Fla.) 18(2), 216–220 (2006).
[Crossref]

2005 (3)

Y. K. Byeun, K. S. Han, and S. C. Choi, “Influence on the growth temperature for one-dimesional GaN nanostructures by halide vapor-phase epitaxy,” J. Ceram. Process. Res. 6(3), 197–200 (2005).

D. Zhuang and J. H. Edgar, “Wet etching of GaN, AIN, and SiC: a review,” Mater. Sci. Eng. Rep. 48(1), 1–46 (2005).
[Crossref]

Y. D. Wang, S. J. Chua, S. Tripathy, M. S. Sander, P. Chen, and C. G. Fonstad, “High optical quality GaN nanopillar arrays,” Appl. Phys. Lett. 86(7), 071917 (2005).
[Crossref]

2004 (1)

H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004).
[Crossref]

2002 (1)

J. Wu, W. Walukiewicz, K. M. Yu, J. W. Ager, E. E. Haller, H. Lu, and W. J. Schaff, “Small band gap bowing in In1-xGaxN alloys,” Appl. Phys. Lett. 80(25), 4741–4743 (2002).
[Crossref]

2001 (1)

S. J. Chua, H. W. Choi, J. Zhang, and P. Li, “Vacancy effects on plasma-induced damage to n-type GaN,” Phys. Rev. B 64(20), 205302 (2001).
[Crossref]

2000 (1)

H. W. Choi, S. J. Chua, A. Raman, J. S. Pan, and A. T. S. Wee, “Plasma-induced damage to n-type GaN,” Appl. Phys. Lett. 77(12), 1795–1797 (2000).
[Crossref]

1998 (1)

D. A. Stocker, E. F. Schubert, and J. M. Redwing, “Crystallographic wet chemical etching of GaN,” Appl. Phys. Lett. 73(18), 2654–2656 (1998).
[Crossref]

Ager, J. W.

J. Wu, W. Walukiewicz, K. M. Yu, J. W. Ager, E. E. Haller, H. Lu, and W. J. Schaff, “Small band gap bowing in In1-xGaxN alloys,” Appl. Phys. Lett. 80(25), 4741–4743 (2002).
[Crossref]

Allerman, A. A.

M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009).
[Crossref]

Aloni, S.

T. Kuykendall, P. Ulrich, S. Aloni, and P. Yang, “Complete composition tunability of InGaN nanowires using a combinatorial approach,” Nat. Mater. 6(12), 951–956 (2007).
[Crossref] [PubMed]

Anderson, R. J.

A. A. Talin, G. T. Wang, E. Lai, and R. J. Anderson, “Correlation of growth temperature, photoluminescence, and resistivity in GaN nanowires,” Appl. Phys. Lett. 92(9), 093105 (2008).
[Crossref]

G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology 17(23), 5773–5780 (2006).
[Crossref]

Armstrong, A.

A. Armstrong, Q. Li, Y. Lin, A. A. Talin, and G. T. Wang, “GaN nanowire surface state observed using deep level optical spectroscopy,” Appl. Phys. Lett. 96(16), 163106 (2010).
[Crossref]

Arslan, I.

G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology 17(23), 5773–5780 (2006).
[Crossref]

Aubry, R.

S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett. 93(21), 212107 (2008).
[Crossref]

Baird, L.

L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 98(13), 132104 (2011).
[Crossref]

Banas, M. A.

M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009).
[Crossref]

Barbet, S.

S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett. 93(21), 212107 (2008).
[Crossref]

Bogart, K. H. A.

M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009).
[Crossref]

Botton, G. A.

H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011).
[Crossref] [PubMed]

Byeun, Y. K.

Y. K. Byeun, K. S. Han, and S. C. Choi, “Influence on the growth temperature for one-dimesional GaN nanostructures by halide vapor-phase epitaxy,” J. Ceram. Process. Res. 6(3), 197–200 (2005).

Chang, L. C.

C. H. Kuo, L. C. Chang, C. W. Kuo, and G. C. Chi, “Efficiency improvement of GaN-based light-emitting diode prepared on GaN nanorod template,” IEEE Photon. Technol. Lett. 22(4), 257–259 (2010).
[Crossref]

Chen, C. P.

Chen, H. Y.

H. W. Lin, Y. J. Lu, H. Y. Chen, H. M. Lee, and S. Gwo, “InGaN/GaN nanorod array white light-emitting diode,” Appl. Phys. Lett. 97(7), 073101 (2010).
[Crossref]

Chen, L. Y.

Chen, P.

Y. D. Wang, S. J. Chua, S. Tripathy, M. S. Sander, P. Chen, and C. G. Fonstad, “High optical quality GaN nanopillar arrays,” Appl. Phys. Lett. 86(7), 071917 (2005).
[Crossref]

Cheng, Y. W.

Chi, G. C.

C. H. Kuo, L. C. Chang, C. W. Kuo, and G. C. Chi, “Efficiency improvement of GaN-based light-emitting diode prepared on GaN nanorod template,” IEEE Photon. Technol. Lett. 22(4), 257–259 (2010).
[Crossref]

Chin, A. H.

H. W. Li, A. H. Chin, and M. K. Sunkara, “Direction-dependent homoepitaxial growth of GaN nanowires,” Adv. Mater. (Deerfield Beach Fla.) 18(2), 216–220 (2006).
[Crossref]

Chiu, C. H.

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
[Crossref]

Cho, Y.-H.

H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004).
[Crossref]

Choi, H. W.

S. J. Chua, H. W. Choi, J. Zhang, and P. Li, “Vacancy effects on plasma-induced damage to n-type GaN,” Phys. Rev. B 64(20), 205302 (2001).
[Crossref]

H. W. Choi, S. J. Chua, A. Raman, J. S. Pan, and A. T. S. Wee, “Plasma-induced damage to n-type GaN,” Appl. Phys. Lett. 77(12), 1795–1797 (2000).
[Crossref]

Choi, S. C.

Y. K. Byeun, K. S. Han, and S. C. Choi, “Influence on the growth temperature for one-dimesional GaN nanostructures by halide vapor-phase epitaxy,” J. Ceram. Process. Res. 6(3), 197–200 (2005).

Chu, J. T.

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
[Crossref]

Chua, S. J.

Y. D. Wang, S. J. Chua, S. Tripathy, M. S. Sander, P. Chen, and C. G. Fonstad, “High optical quality GaN nanopillar arrays,” Appl. Phys. Lett. 86(7), 071917 (2005).
[Crossref]

S. J. Chua, H. W. Choi, J. Zhang, and P. Li, “Vacancy effects on plasma-induced damage to n-type GaN,” Phys. Rev. B 64(20), 205302 (2001).
[Crossref]

H. W. Choi, S. J. Chua, A. Raman, J. S. Pan, and A. T. S. Wee, “Plasma-induced damage to n-type GaN,” Appl. Phys. Lett. 77(12), 1795–1797 (2000).
[Crossref]

Chung, K. S.

H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004).
[Crossref]

Cole, R. A.

L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 98(13), 132104 (2011).
[Crossref]

Couillard, M.

H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011).
[Crossref] [PubMed]

Crawford, M. H.

M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009).
[Crossref]

Creighton, J. R.

G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology 17(23), 5773–5780 (2006).
[Crossref]

Cross, K. C.

M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009).
[Crossref]

Cui, K.

H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011).
[Crossref] [PubMed]

Deresmes, D.

S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett. 93(21), 212107 (2008).
[Crossref]

di Forte-Poisson, M. A.

S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett. 93(21), 212107 (2008).
[Crossref]

Edgar, J. H.

D. Zhuang and J. H. Edgar, “Wet etching of GaN, AIN, and SiC: a review,” Mater. Sci. Eng. Rep. 48(1), 1–46 (2005).
[Crossref]

Fathololoumi, S.

H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011).
[Crossref] [PubMed]

Figiel, J. J.

Q. Li, J. J. Figiel, and G. T. Wang, “Dislocation density reduction in GaN by dislocation filtering through a self-assembled monolayer of silica microspheres,” Appl. Phys. Lett. 94(23), 231105 (2009).
[Crossref]

Fischer, A. J.

P. C. Upadhya, Q. M. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” Semicond. Sci. Technol. 25(2), 024017 (2010).
[Crossref]

Fonstad, C. G.

Y. D. Wang, S. J. Chua, S. Tripathy, M. S. Sander, P. Chen, and C. G. Fonstad, “High optical quality GaN nanopillar arrays,” Appl. Phys. Lett. 86(7), 071917 (2005).
[Crossref]

Garnett, E.

E. Garnett and P. Yang, “Light trapping in silicon nanowire solar cells,” Nano Lett. 10(3), 1082–1087 (2010).
[Crossref] [PubMed]

Gwo, S.

H. W. Lin, Y. J. Lu, H. Y. Chen, H. M. Lee, and S. Gwo, “InGaN/GaN nanorod array white light-emitting diode,” Appl. Phys. Lett. 97(7), 073101 (2010).
[Crossref]

Haegel, N. M.

L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 98(13), 132104 (2011).
[Crossref]

Haller, E. E.

J. Wu, W. Walukiewicz, K. M. Yu, J. W. Ager, E. E. Haller, H. Lu, and W. J. Schaff, “Small band gap bowing in In1-xGaxN alloys,” Appl. Phys. Lett. 80(25), 4741–4743 (2002).
[Crossref]

Han, K. S.

Y. K. Byeun, K. S. Han, and S. C. Choi, “Influence on the growth temperature for one-dimesional GaN nanostructures by halide vapor-phase epitaxy,” J. Ceram. Process. Res. 6(3), 197–200 (2005).

Han, X.

H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011).
[Crossref] [PubMed]

Hersee, S. D.

A. A. Talin, F. Léonard, B. S. Swartzentruber, X. Wang, and S. D. Hersee, “Unusually strong space-charge-limited current in thin wires,” Phys. Rev. Lett. 101(7), 076802 (2008).
[Crossref] [PubMed]

S. D. Hersee, X. Y. Sun, and X. Wang, “The controlled growth of GaN nanowires,” Nano Lett. 6(8), 1808–1811 (2006).
[Crossref] [PubMed]

Hsieh, M. Y.

Hsueh, T. H.

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
[Crossref]

Huang, H. W.

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
[Crossref]

Huang, J.

Ishizawa, S.

K. Kishino, A. Kikuchi, H. Sekiguchi, and S. Ishizawa, “InGaN/GaN nanocolumn LEDs emitting from blue to red,” Proc. SPIE 6473, 64730T (2007).
[Crossref]

Jacquet, J. C.

S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett. 93(21), 212107 (2008).
[Crossref]

Kang, T. W.

H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004).
[Crossref]

Kao, C. C.

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
[Crossref]

Ke, M. Y.

Kikuchi, A.

H. Sekiguchi, K. Kishino, and A. Kikuchi, “Emission color control from blue to red with nanocolumn diameter of InGaN/GaN nanocolumn arrays grown on same substrate,” Appl. Phys. Lett. 96(23), 231104 (2010).
[Crossref]

K. Kishino, A. Kikuchi, H. Sekiguchi, and S. Ishizawa, “InGaN/GaN nanocolumn LEDs emitting from blue to red,” Proc. SPIE 6473, 64730T (2007).
[Crossref]

Kim, D. Y.

H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004).
[Crossref]

Kim, H.-M.

H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004).
[Crossref]

Kim, S. I.

H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004).
[Crossref]

Kishino, K.

H. Sekiguchi, K. Kishino, and A. Kikuchi, “Emission color control from blue to red with nanocolumn diameter of InGaN/GaN nanocolumn arrays grown on same substrate,” Appl. Phys. Lett. 96(23), 231104 (2010).
[Crossref]

K. Kishino, A. Kikuchi, H. Sekiguchi, and S. Ishizawa, “InGaN/GaN nanocolumn LEDs emitting from blue to red,” Proc. SPIE 6473, 64730T (2007).
[Crossref]

Kuo, C. H.

C. H. Kuo, L. C. Chang, C. W. Kuo, and G. C. Chi, “Efficiency improvement of GaN-based light-emitting diode prepared on GaN nanorod template,” IEEE Photon. Technol. Lett. 22(4), 257–259 (2010).
[Crossref]

Kuo, C. W.

C. H. Kuo, L. C. Chang, C. W. Kuo, and G. C. Chi, “Efficiency improvement of GaN-based light-emitting diode prepared on GaN nanorod template,” IEEE Photon. Technol. Lett. 22(4), 257–259 (2010).
[Crossref]

Kuo, H. C.

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
[Crossref]

Kuykendall, T.

T. Kuykendall, P. Ulrich, S. Aloni, and P. Yang, “Complete composition tunability of InGaN nanowires using a combinatorial approach,” Nat. Mater. 6(12), 951–956 (2007).
[Crossref] [PubMed]

Lai, C. F.

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
[Crossref]

Lai, E.

A. A. Talin, G. T. Wang, E. Lai, and R. J. Anderson, “Correlation of growth temperature, photoluminescence, and resistivity in GaN nanowires,” Appl. Phys. Lett. 92(9), 093105 (2008).
[Crossref]

G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology 17(23), 5773–5780 (2006).
[Crossref]

Lee, H.

H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004).
[Crossref]

Lee, H. M.

H. W. Lin, Y. J. Lu, H. Y. Chen, H. M. Lee, and S. Gwo, “InGaN/GaN nanorod array white light-emitting diode,” Appl. Phys. Lett. 97(7), 073101 (2010).
[Crossref]

Léonard, F.

A. A. Talin, F. Léonard, B. S. Swartzentruber, X. Wang, and S. D. Hersee, “Unusually strong space-charge-limited current in thin wires,” Phys. Rev. Lett. 101(7), 076802 (2008).
[Crossref] [PubMed]

Li, H. W.

H. W. Li, A. H. Chin, and M. K. Sunkara, “Direction-dependent homoepitaxial growth of GaN nanowires,” Adv. Mater. (Deerfield Beach Fla.) 18(2), 216–220 (2006).
[Crossref]

Li, P.

S. J. Chua, H. W. Choi, J. Zhang, and P. Li, “Vacancy effects on plasma-induced damage to n-type GaN,” Phys. Rev. B 64(20), 205302 (2001).
[Crossref]

Li, Q.

A. Armstrong, Q. Li, Y. Lin, A. A. Talin, and G. T. Wang, “GaN nanowire surface state observed using deep level optical spectroscopy,” Appl. Phys. Lett. 96(16), 163106 (2010).
[Crossref]

Q. Li, J. J. Figiel, and G. T. Wang, “Dislocation density reduction in GaN by dislocation filtering through a self-assembled monolayer of silica microspheres,” Appl. Phys. Lett. 94(23), 231105 (2009).
[Crossref]

Li, Q. M.

L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 98(13), 132104 (2011).
[Crossref]

Q. M. Li and G. T. Wang, “Strain influenced indium composition distribution in GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 97(18), 181107 (2010).
[Crossref]

P. C. Upadhya, Q. M. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” Semicond. Sci. Technol. 25(2), 024017 (2010).
[Crossref]

Lin, C. F.

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
[Crossref]

Lin, H. W.

H. W. Lin, Y. J. Lu, H. Y. Chen, H. M. Lee, and S. Gwo, “InGaN/GaN nanorod array white light-emitting diode,” Appl. Phys. Lett. 97(7), 073101 (2010).
[Crossref]

Lin, Y.

A. Armstrong, Q. Li, Y. Lin, A. A. Talin, and G. T. Wang, “GaN nanowire surface state observed using deep level optical spectroscopy,” Appl. Phys. Lett. 96(16), 163106 (2010).
[Crossref]

Lu, H.

J. Wu, W. Walukiewicz, K. M. Yu, J. W. Ager, E. E. Haller, H. Lu, and W. J. Schaff, “Small band gap bowing in In1-xGaxN alloys,” Appl. Phys. Lett. 80(25), 4741–4743 (2002).
[Crossref]

Lu, T. C.

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
[Crossref]

Lu, Y. J.

H. W. Lin, Y. J. Lu, H. Y. Chen, H. M. Lee, and S. Gwo, “InGaN/GaN nanorod array white light-emitting diode,” Appl. Phys. Lett. 97(7), 073101 (2010).
[Crossref]

Melin, T.

S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett. 93(21), 212107 (2008).
[Crossref]

Mi, Z.

H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011).
[Crossref] [PubMed]

Miller, M. A.

M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009).
[Crossref]

Nguyen, H. P. T.

H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011).
[Crossref] [PubMed]

Ong, C. P.

L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 98(13), 132104 (2011).
[Crossref]

Pan, J. S.

H. W. Choi, S. J. Chua, A. Raman, J. S. Pan, and A. T. S. Wee, “Plasma-induced damage to n-type GaN,” Appl. Phys. Lett. 77(12), 1795–1797 (2000).
[Crossref]

Peng, L. H.

Prasankumar, R. P.

P. C. Upadhya, Q. M. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” Semicond. Sci. Technol. 25(2), 024017 (2010).
[Crossref]

Raman, A.

H. W. Choi, S. J. Chua, A. Raman, J. S. Pan, and A. T. S. Wee, “Plasma-induced damage to n-type GaN,” Appl. Phys. Lett. 77(12), 1795–1797 (2000).
[Crossref]

Redwing, J. M.

D. A. Stocker, E. F. Schubert, and J. M. Redwing, “Crystallographic wet chemical etching of GaN,” Appl. Phys. Lett. 73(18), 2654–2656 (1998).
[Crossref]

Ryu, S. R.

H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004).
[Crossref]

Sander, M. S.

Y. D. Wang, S. J. Chua, S. Tripathy, M. S. Sander, P. Chen, and C. G. Fonstad, “High optical quality GaN nanopillar arrays,” Appl. Phys. Lett. 86(7), 071917 (2005).
[Crossref]

Schaff, W. J.

J. Wu, W. Walukiewicz, K. M. Yu, J. W. Ager, E. E. Haller, H. Lu, and W. J. Schaff, “Small band gap bowing in In1-xGaxN alloys,” Appl. Phys. Lett. 80(25), 4741–4743 (2002).
[Crossref]

Schubert, E. F.

D. A. Stocker, E. F. Schubert, and J. M. Redwing, “Crystallographic wet chemical etching of GaN,” Appl. Phys. Lett. 73(18), 2654–2656 (1998).
[Crossref]

Sekiguchi, H.

H. Sekiguchi, K. Kishino, and A. Kikuchi, “Emission color control from blue to red with nanocolumn diameter of InGaN/GaN nanocolumn arrays grown on same substrate,” Appl. Phys. Lett. 96(23), 231104 (2010).
[Crossref]

K. Kishino, A. Kikuchi, H. Sekiguchi, and S. Ishizawa, “InGaN/GaN nanocolumn LEDs emitting from blue to red,” Proc. SPIE 6473, 64730T (2007).
[Crossref]

Shul, R. J.

M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009).
[Crossref]

Stevens, J.

M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009).
[Crossref]

Stocker, D. A.

D. A. Stocker, E. F. Schubert, and J. M. Redwing, “Crystallographic wet chemical etching of GaN,” Appl. Phys. Lett. 73(18), 2654–2656 (1998).
[Crossref]

Sun, X. Y.

S. D. Hersee, X. Y. Sun, and X. Wang, “The controlled growth of GaN nanowires,” Nano Lett. 6(8), 1808–1811 (2006).
[Crossref] [PubMed]

Sunkara, M. K.

H. W. Li, A. H. Chin, and M. K. Sunkara, “Direction-dependent homoepitaxial growth of GaN nanowires,” Adv. Mater. (Deerfield Beach Fla.) 18(2), 216–220 (2006).
[Crossref]

Swartzentruber, B. S.

A. A. Talin, F. Léonard, B. S. Swartzentruber, X. Wang, and S. D. Hersee, “Unusually strong space-charge-limited current in thin wires,” Phys. Rev. Lett. 101(7), 076802 (2008).
[Crossref] [PubMed]

Talin, A. A.

L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 98(13), 132104 (2011).
[Crossref]

A. Armstrong, Q. Li, Y. Lin, A. A. Talin, and G. T. Wang, “GaN nanowire surface state observed using deep level optical spectroscopy,” Appl. Phys. Lett. 96(16), 163106 (2010).
[Crossref]

A. A. Talin, G. T. Wang, E. Lai, and R. J. Anderson, “Correlation of growth temperature, photoluminescence, and resistivity in GaN nanowires,” Appl. Phys. Lett. 92(9), 093105 (2008).
[Crossref]

A. A. Talin, F. Léonard, B. S. Swartzentruber, X. Wang, and S. D. Hersee, “Unusually strong space-charge-limited current in thin wires,” Phys. Rev. Lett. 101(7), 076802 (2008).
[Crossref] [PubMed]

G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology 17(23), 5773–5780 (2006).
[Crossref]

Taylor, A. J.

P. C. Upadhya, Q. M. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” Semicond. Sci. Technol. 25(2), 024017 (2010).
[Crossref]

Theron, D.

S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett. 93(21), 212107 (2008).
[Crossref]

Tripathy, S.

Y. D. Wang, S. J. Chua, S. Tripathy, M. S. Sander, P. Chen, and C. G. Fonstad, “High optical quality GaN nanopillar arrays,” Appl. Phys. Lett. 86(7), 071917 (2005).
[Crossref]

Ulrich, P.

T. Kuykendall, P. Ulrich, S. Aloni, and P. Yang, “Complete composition tunability of InGaN nanowires using a combinatorial approach,” Nat. Mater. 6(12), 951–956 (2007).
[Crossref] [PubMed]

Upadhya, P. C.

P. C. Upadhya, Q. M. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” Semicond. Sci. Technol. 25(2), 024017 (2010).
[Crossref]

Walukiewicz, W.

J. Wu, W. Walukiewicz, K. M. Yu, J. W. Ager, E. E. Haller, H. Lu, and W. J. Schaff, “Small band gap bowing in In1-xGaxN alloys,” Appl. Phys. Lett. 80(25), 4741–4743 (2002).
[Crossref]

Wang, C. Y.

Wang, G. T.

L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 98(13), 132104 (2011).
[Crossref]

Q. M. Li and G. T. Wang, “Strain influenced indium composition distribution in GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 97(18), 181107 (2010).
[Crossref]

P. C. Upadhya, Q. M. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” Semicond. Sci. Technol. 25(2), 024017 (2010).
[Crossref]

A. Armstrong, Q. Li, Y. Lin, A. A. Talin, and G. T. Wang, “GaN nanowire surface state observed using deep level optical spectroscopy,” Appl. Phys. Lett. 96(16), 163106 (2010).
[Crossref]

Q. Li, J. J. Figiel, and G. T. Wang, “Dislocation density reduction in GaN by dislocation filtering through a self-assembled monolayer of silica microspheres,” Appl. Phys. Lett. 94(23), 231105 (2009).
[Crossref]

A. A. Talin, G. T. Wang, E. Lai, and R. J. Anderson, “Correlation of growth temperature, photoluminescence, and resistivity in GaN nanowires,” Appl. Phys. Lett. 92(9), 093105 (2008).
[Crossref]

G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology 17(23), 5773–5780 (2006).
[Crossref]

Wang, S. C.

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
[Crossref]

Wang, X.

A. A. Talin, F. Léonard, B. S. Swartzentruber, X. Wang, and S. D. Hersee, “Unusually strong space-charge-limited current in thin wires,” Phys. Rev. Lett. 101(7), 076802 (2008).
[Crossref] [PubMed]

S. D. Hersee, X. Y. Sun, and X. Wang, “The controlled growth of GaN nanowires,” Nano Lett. 6(8), 1808–1811 (2006).
[Crossref] [PubMed]

Wang, Y. D.

Y. D. Wang, S. J. Chua, S. Tripathy, M. S. Sander, P. Chen, and C. G. Fonstad, “High optical quality GaN nanopillar arrays,” Appl. Phys. Lett. 86(7), 071917 (2005).
[Crossref]

Wee, A. T. S.

H. W. Choi, S. J. Chua, A. Raman, J. S. Pan, and A. T. S. Wee, “Plasma-induced damage to n-type GaN,” Appl. Phys. Lett. 77(12), 1795–1797 (2000).
[Crossref]

Werder, D. J.

G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology 17(23), 5773–5780 (2006).
[Crossref]

Wu, H. M.

Wu, J.

J. Wu, W. Walukiewicz, K. M. Yu, J. W. Ager, E. E. Haller, H. Lu, and W. J. Schaff, “Small band gap bowing in In1-xGaxN alloys,” Appl. Phys. Lett. 80(25), 4741–4743 (2002).
[Crossref]

Yang, P.

E. Garnett and P. Yang, “Light trapping in silicon nanowire solar cells,” Nano Lett. 10(3), 1082–1087 (2010).
[Crossref] [PubMed]

T. Kuykendall, P. Ulrich, S. Aloni, and P. Yang, “Complete composition tunability of InGaN nanowires using a combinatorial approach,” Nat. Mater. 6(12), 951–956 (2007).
[Crossref] [PubMed]

Yu, C. C.

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
[Crossref]

Yu, K. M.

J. Wu, W. Walukiewicz, K. M. Yu, J. W. Ager, E. E. Haller, H. Lu, and W. J. Schaff, “Small band gap bowing in In1-xGaxN alloys,” Appl. Phys. Lett. 80(25), 4741–4743 (2002).
[Crossref]

Zhang, J.

S. J. Chua, H. W. Choi, J. Zhang, and P. Li, “Vacancy effects on plasma-induced damage to n-type GaN,” Phys. Rev. B 64(20), 205302 (2001).
[Crossref]

Zhang, S.

H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011).
[Crossref] [PubMed]

Zhuang, D.

D. Zhuang and J. H. Edgar, “Wet etching of GaN, AIN, and SiC: a review,” Mater. Sci. Eng. Rep. 48(1), 1–46 (2005).
[Crossref]

Adv. Mater. (Deerfield Beach Fla.) (1)

H. W. Li, A. H. Chin, and M. K. Sunkara, “Direction-dependent homoepitaxial growth of GaN nanowires,” Adv. Mater. (Deerfield Beach Fla.) 18(2), 216–220 (2006).
[Crossref]

Appl. Phys. Lett. (12)

J. Wu, W. Walukiewicz, K. M. Yu, J. W. Ager, E. E. Haller, H. Lu, and W. J. Schaff, “Small band gap bowing in In1-xGaxN alloys,” Appl. Phys. Lett. 80(25), 4741–4743 (2002).
[Crossref]

S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett. 93(21), 212107 (2008).
[Crossref]

H. W. Choi, S. J. Chua, A. Raman, J. S. Pan, and A. T. S. Wee, “Plasma-induced damage to n-type GaN,” Appl. Phys. Lett. 77(12), 1795–1797 (2000).
[Crossref]

A. Armstrong, Q. Li, Y. Lin, A. A. Talin, and G. T. Wang, “GaN nanowire surface state observed using deep level optical spectroscopy,” Appl. Phys. Lett. 96(16), 163106 (2010).
[Crossref]

L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 98(13), 132104 (2011).
[Crossref]

Q. M. Li and G. T. Wang, “Strain influenced indium composition distribution in GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 97(18), 181107 (2010).
[Crossref]

H. W. Lin, Y. J. Lu, H. Y. Chen, H. M. Lee, and S. Gwo, “InGaN/GaN nanorod array white light-emitting diode,” Appl. Phys. Lett. 97(7), 073101 (2010).
[Crossref]

H. Sekiguchi, K. Kishino, and A. Kikuchi, “Emission color control from blue to red with nanocolumn diameter of InGaN/GaN nanocolumn arrays grown on same substrate,” Appl. Phys. Lett. 96(23), 231104 (2010).
[Crossref]

A. A. Talin, G. T. Wang, E. Lai, and R. J. Anderson, “Correlation of growth temperature, photoluminescence, and resistivity in GaN nanowires,” Appl. Phys. Lett. 92(9), 093105 (2008).
[Crossref]

Q. Li, J. J. Figiel, and G. T. Wang, “Dislocation density reduction in GaN by dislocation filtering through a self-assembled monolayer of silica microspheres,” Appl. Phys. Lett. 94(23), 231105 (2009).
[Crossref]

Y. D. Wang, S. J. Chua, S. Tripathy, M. S. Sander, P. Chen, and C. G. Fonstad, “High optical quality GaN nanopillar arrays,” Appl. Phys. Lett. 86(7), 071917 (2005).
[Crossref]

D. A. Stocker, E. F. Schubert, and J. M. Redwing, “Crystallographic wet chemical etching of GaN,” Appl. Phys. Lett. 73(18), 2654–2656 (1998).
[Crossref]

IEEE Photon. Technol. Lett. (1)

C. H. Kuo, L. C. Chang, C. W. Kuo, and G. C. Chi, “Efficiency improvement of GaN-based light-emitting diode prepared on GaN nanorod template,” IEEE Photon. Technol. Lett. 22(4), 257–259 (2010).
[Crossref]

J. Ceram. Process. Res. (1)

Y. K. Byeun, K. S. Han, and S. C. Choi, “Influence on the growth temperature for one-dimesional GaN nanostructures by halide vapor-phase epitaxy,” J. Ceram. Process. Res. 6(3), 197–200 (2005).

J. Electron. Mater. (1)

M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009).
[Crossref]

Mater. Sci. Eng. Rep. (1)

D. Zhuang and J. H. Edgar, “Wet etching of GaN, AIN, and SiC: a review,” Mater. Sci. Eng. Rep. 48(1), 1–46 (2005).
[Crossref]

Nano Lett. (4)

S. D. Hersee, X. Y. Sun, and X. Wang, “The controlled growth of GaN nanowires,” Nano Lett. 6(8), 1808–1811 (2006).
[Crossref] [PubMed]

H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011).
[Crossref] [PubMed]

H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004).
[Crossref]

E. Garnett and P. Yang, “Light trapping in silicon nanowire solar cells,” Nano Lett. 10(3), 1082–1087 (2010).
[Crossref] [PubMed]

Nanotechnology (2)

G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology 17(23), 5773–5780 (2006).
[Crossref]

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007).
[Crossref]

Nat. Mater. (1)

T. Kuykendall, P. Ulrich, S. Aloni, and P. Yang, “Complete composition tunability of InGaN nanowires using a combinatorial approach,” Nat. Mater. 6(12), 951–956 (2007).
[Crossref] [PubMed]

Opt. Express (1)

Phys. Rev. B (1)

S. J. Chua, H. W. Choi, J. Zhang, and P. Li, “Vacancy effects on plasma-induced damage to n-type GaN,” Phys. Rev. B 64(20), 205302 (2001).
[Crossref]

Phys. Rev. Lett. (1)

A. A. Talin, F. Léonard, B. S. Swartzentruber, X. Wang, and S. D. Hersee, “Unusually strong space-charge-limited current in thin wires,” Phys. Rev. Lett. 101(7), 076802 (2008).
[Crossref] [PubMed]

Proc. SPIE (1)

K. Kishino, A. Kikuchi, H. Sekiguchi, and S. Ishizawa, “InGaN/GaN nanocolumn LEDs emitting from blue to red,” Proc. SPIE 6473, 64730T (2007).
[Crossref]

Semicond. Sci. Technol. (1)

P. C. Upadhya, Q. M. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” Semicond. Sci. Technol. 25(2), 024017 (2010).
[Crossref]

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Figures (5)

Fig. 1
Fig. 1 SEM images of (a) a planar LED wafer covered with a monolayer of self-assembled silica spheres, (b) tapered nanorod LEDs created by plasma etch, and (c) “flashlight” shaped nanorod LEDs array following wet etch. (d) A STEM image of nanorod “flashlight” LEDs showing the position of the InGaN MQWs (bright stripes).
Fig. 2
Fig. 2 PL spectra of GaN thin film (solid black) and GaN nanorods after plasma etch (dashed-dotted red) and subsequent wet etch (dotted blue).
Fig. 3
Fig. 3 TEM images of etched nanorod LED structures. A dislocation is indicated by the arrow in (a).
Fig. 4
Fig. 4 MQW PL of (a) nanorod LEDs and (b) planar LED. (c) MQW PL peak position plotted as a function of pump power for planar LEDs and nanorod LEDs.
Fig. 5
Fig. 5 The IQE of the planar and nanorod LEDs plotted as a function of the optical pumping power.

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