Abstract

Vertically aligned silicon nanowires (SiNWs) were cost-effectively formed on a four-inch silicon wafer using a simple room temperature approach, i.e., metal-assisted electroless etching. Tapering the NWs by post-KOH dipping achieved separation of each NW from the bunched NW, resulting in a strong enhancement of broadband optical absorption. As electroless etching time increases, the optical crossover feature was observed in the tradeoff between enhanced light trapping (by graded-refractive index during initial tapering) and deteriorated reflectance (by decreasing the areal density of NWs during later tapering). Compared to the bunched SiNWs, tapered NW solar cells demonstrated superior photovoltaic characteristics, such as a short circuit current of 17.67 mA/cm2 and a cell conversion efficiency of ~6.56% under 1.5 AM illumination.

© 2010 OSA

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    [CrossRef]
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2010 (2)

H.-D. Um, J.-Y. Jung, H.-S. Seo, K.-T. Park, S.-W. Jee, S. A. Moiz, and J.-H. Lee, “Silicon nanowire array solar cell prepared by metal induced electroless etching with a novel processing technology,” Jpn. J. Appl. Phys. 49(4), 04DN02 (2010).
[CrossRef]

Y. M. Song, J. S. Yu, and Y. T. Lee, “Antireflective submicrometer gratings on thin-film silicon solar cells for light-absorption enhancement,” Opt. Lett. 35(3), 276–278 (2010).
[CrossRef] [PubMed]

2009 (6)

C. Lin and M. L. Povinelli, “Optical absorption enhancement in silicon nanowire arrays with a large lattice constant for photovoltaic applications,” Opt. Express 17(22), 19371–19381 (2009).
[CrossRef] [PubMed]

X. Li, H.-S. Seo, H.-D. Um, S.-W. Jee, Y. W. Cho, B. Yoo, and J.-H. Lee, “A periodic array of silicon pillars fabricated by photoelectrochemical etching,” Electrochim. Acta 54(27), 6978–6982 (2009).
[CrossRef]

V. Sivakov, G. Andrä, A. Gawlik, A. Berger, J. Plentz, F. Falk, and S. H. Christiansen, “Silicon nanowire-based solar cells on glass: synthesis, optical properties, and cell parameters,” Nano Lett. 9(4), 1549–1554 (2009).
[CrossRef] [PubMed]

J. Zhu, Z. Yu, G. F. Burkhard, C. M. Hsu, S. T. Connor, Y. Xu, Q. Wang, M. McGehee, S. Fan, and Y. Cui, “Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays,” Nano Lett. 9(1), 279–282 (2009).
[CrossRef]

S. L. Diedenhofen, G. Vecchi, R. E. Algra, A. Hartsuiker, O. L. Muskens, G. Immink, E. P. A. M. Bakkers, W. L. Vos, and J. G. Rivas, “Broad-band and omnidirectional antireflection coating based on semiconductor nanorods,” Adv. Mater. 21(9), 973–978 (2009).
[CrossRef]

J. Li, H. Yu, S. M. Wong, G. Zhang, X. Sun, P. G. Lo, and D.-L. Kwong, “Design guidelines of periodic Si nanowire arrays for solar cell application,” Appl. Phys. Lett. 95, 033102 (2009).
[CrossRef]

2008 (2)

G. Chen, J. Wu, Q. Lu, H. R. Gutierrez, Q. Xiong, M. E. Pellen, J. S. Petko, D. H. Werner, and P. C. Eklund, “Optical antenna effect in semiconducting nanowires,” Nano Lett. 8(5), 1341–1346 (2008).
[CrossRef] [PubMed]

E. C. Garnett and P. D. Yang, “Silicon nanowire radial p-n junction solar cells,” J. Am. Chem. Soc. 130(29), 9224–9225 (2008).
[CrossRef] [PubMed]

2007 (3)

B. Tian, X. Zheng, T. J. Kempa, Y. Fang, N. Yu, G. Yu, J. Huang, and C. M. Lieber, “Coaxial silicon nanowires as solar cells and nanoelectronic power sources,” Nature 449(7164), 885–889 (2007).
[CrossRef] [PubMed]

L. Hu and G. Chen, “Analysis of optical absorption in silicon nanowire arrays for photovoltaic applications,” Nano Lett. 7(11), 3249–3252 (2007).
[CrossRef] [PubMed]

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

2005 (3)

B. M. Kayes, H. A. Atwater, and N. S. Lewis, “Comparison of the device physics principles of planar and radial p-n junction nanorod solar cells,” J. Appl. Phys. 97(11), 114302 (2005).
[CrossRef]

K. Peng, Y. Xu, Y. Wu, Y. Yan, S. T. Lee, and J. Zhu, “Aligned single-crystalline Si nanowire arrays for photovoltaic applications,” Small 1(11), 1062–1067 (2005).
[CrossRef]

K. Q. Peng, Y. Wu, H. Fang, X. Zhong, Y. Xu, and J. Zhu, “Uniform, axial-orientation alignment of one-dimensional single-crystal silicon nanostructure arrays,” Angew. Chem. Int. Ed. Engl. 44(18), 2737–2742 (2005).
[CrossRef] [PubMed]

2001 (1)

P. K. Singh, R. Kumar, M. Lal, S. N. Singh, and B. K. Das, “Effectiveness of silicon in aqueous alkaline solutions,” Sol. Energy Mater. Sol. Cells 70, 103 (2001).
[CrossRef]

1999 (1)

Algra, R. E.

S. L. Diedenhofen, G. Vecchi, R. E. Algra, A. Hartsuiker, O. L. Muskens, G. Immink, E. P. A. M. Bakkers, W. L. Vos, and J. G. Rivas, “Broad-band and omnidirectional antireflection coating based on semiconductor nanorods,” Adv. Mater. 21(9), 973–978 (2009).
[CrossRef]

Andrä, G.

V. Sivakov, G. Andrä, A. Gawlik, A. Berger, J. Plentz, F. Falk, and S. H. Christiansen, “Silicon nanowire-based solar cells on glass: synthesis, optical properties, and cell parameters,” Nano Lett. 9(4), 1549–1554 (2009).
[CrossRef] [PubMed]

Atwater, H. A.

B. M. Kayes, H. A. Atwater, and N. S. Lewis, “Comparison of the device physics principles of planar and radial p-n junction nanorod solar cells,” J. Appl. Phys. 97(11), 114302 (2005).
[CrossRef]

Bakkers, E. P. A. M.

S. L. Diedenhofen, G. Vecchi, R. E. Algra, A. Hartsuiker, O. L. Muskens, G. Immink, E. P. A. M. Bakkers, W. L. Vos, and J. G. Rivas, “Broad-band and omnidirectional antireflection coating based on semiconductor nanorods,” Adv. Mater. 21(9), 973–978 (2009).
[CrossRef]

Balch, J.

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

Berger, A.

V. Sivakov, G. Andrä, A. Gawlik, A. Berger, J. Plentz, F. Falk, and S. H. Christiansen, “Silicon nanowire-based solar cells on glass: synthesis, optical properties, and cell parameters,” Nano Lett. 9(4), 1549–1554 (2009).
[CrossRef] [PubMed]

Burkhard, G. F.

J. Zhu, Z. Yu, G. F. Burkhard, C. M. Hsu, S. T. Connor, Y. Xu, Q. Wang, M. McGehee, S. Fan, and Y. Cui, “Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays,” Nano Lett. 9(1), 279–282 (2009).
[CrossRef]

Chen, G.

G. Chen, J. Wu, Q. Lu, H. R. Gutierrez, Q. Xiong, M. E. Pellen, J. S. Petko, D. H. Werner, and P. C. Eklund, “Optical antenna effect in semiconducting nanowires,” Nano Lett. 8(5), 1341–1346 (2008).
[CrossRef] [PubMed]

L. Hu and G. Chen, “Analysis of optical absorption in silicon nanowire arrays for photovoltaic applications,” Nano Lett. 7(11), 3249–3252 (2007).
[CrossRef] [PubMed]

Cho, Y. W.

X. Li, H.-S. Seo, H.-D. Um, S.-W. Jee, Y. W. Cho, B. Yoo, and J.-H. Lee, “A periodic array of silicon pillars fabricated by photoelectrochemical etching,” Electrochim. Acta 54(27), 6978–6982 (2009).
[CrossRef]

Christiansen, S. H.

V. Sivakov, G. Andrä, A. Gawlik, A. Berger, J. Plentz, F. Falk, and S. H. Christiansen, “Silicon nanowire-based solar cells on glass: synthesis, optical properties, and cell parameters,” Nano Lett. 9(4), 1549–1554 (2009).
[CrossRef] [PubMed]

Codella, P. J.

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

Connor, S. T.

J. Zhu, Z. Yu, G. F. Burkhard, C. M. Hsu, S. T. Connor, Y. Xu, Q. Wang, M. McGehee, S. Fan, and Y. Cui, “Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays,” Nano Lett. 9(1), 279–282 (2009).
[CrossRef]

Cui, Y.

J. Zhu, Z. Yu, G. F. Burkhard, C. M. Hsu, S. T. Connor, Y. Xu, Q. Wang, M. McGehee, S. Fan, and Y. Cui, “Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays,” Nano Lett. 9(1), 279–282 (2009).
[CrossRef]

Das, B. K.

P. K. Singh, R. Kumar, M. Lal, S. N. Singh, and B. K. Das, “Effectiveness of silicon in aqueous alkaline solutions,” Sol. Energy Mater. Sol. Cells 70, 103 (2001).
[CrossRef]

Davuluru, A.

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

Diedenhofen, S. L.

S. L. Diedenhofen, G. Vecchi, R. E. Algra, A. Hartsuiker, O. L. Muskens, G. Immink, E. P. A. M. Bakkers, W. L. Vos, and J. G. Rivas, “Broad-band and omnidirectional antireflection coating based on semiconductor nanorods,” Adv. Mater. 21(9), 973–978 (2009).
[CrossRef]

Eklund, P. C.

G. Chen, J. Wu, Q. Lu, H. R. Gutierrez, Q. Xiong, M. E. Pellen, J. S. Petko, D. H. Werner, and P. C. Eklund, “Optical antenna effect in semiconducting nanowires,” Nano Lett. 8(5), 1341–1346 (2008).
[CrossRef] [PubMed]

Falk, F.

V. Sivakov, G. Andrä, A. Gawlik, A. Berger, J. Plentz, F. Falk, and S. H. Christiansen, “Silicon nanowire-based solar cells on glass: synthesis, optical properties, and cell parameters,” Nano Lett. 9(4), 1549–1554 (2009).
[CrossRef] [PubMed]

Fan, S.

J. Zhu, Z. Yu, G. F. Burkhard, C. M. Hsu, S. T. Connor, Y. Xu, Q. Wang, M. McGehee, S. Fan, and Y. Cui, “Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays,” Nano Lett. 9(1), 279–282 (2009).
[CrossRef]

Fang, H.

K. Q. Peng, Y. Wu, H. Fang, X. Zhong, Y. Xu, and J. Zhu, “Uniform, axial-orientation alignment of one-dimensional single-crystal silicon nanostructure arrays,” Angew. Chem. Int. Ed. Engl. 44(18), 2737–2742 (2005).
[CrossRef] [PubMed]

Fang, Y.

B. Tian, X. Zheng, T. J. Kempa, Y. Fang, N. Yu, G. Yu, J. Huang, and C. M. Lieber, “Coaxial silicon nanowires as solar cells and nanoelectronic power sources,” Nature 449(7164), 885–889 (2007).
[CrossRef] [PubMed]

Fronheiser, J.

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

Garnett, E. C.

E. C. Garnett and P. D. Yang, “Silicon nanowire radial p-n junction solar cells,” J. Am. Chem. Soc. 130(29), 9224–9225 (2008).
[CrossRef] [PubMed]

Gawlik, A.

V. Sivakov, G. Andrä, A. Gawlik, A. Berger, J. Plentz, F. Falk, and S. H. Christiansen, “Silicon nanowire-based solar cells on glass: synthesis, optical properties, and cell parameters,” Nano Lett. 9(4), 1549–1554 (2009).
[CrossRef] [PubMed]

Gutierrez, H. R.

G. Chen, J. Wu, Q. Lu, H. R. Gutierrez, Q. Xiong, M. E. Pellen, J. S. Petko, D. H. Werner, and P. C. Eklund, “Optical antenna effect in semiconducting nanowires,” Nano Lett. 8(5), 1341–1346 (2008).
[CrossRef] [PubMed]

Hane, K.

Hartsuiker, A.

S. L. Diedenhofen, G. Vecchi, R. E. Algra, A. Hartsuiker, O. L. Muskens, G. Immink, E. P. A. M. Bakkers, W. L. Vos, and J. G. Rivas, “Broad-band and omnidirectional antireflection coating based on semiconductor nanorods,” Adv. Mater. 21(9), 973–978 (2009).
[CrossRef]

Hsu, C. M.

J. Zhu, Z. Yu, G. F. Burkhard, C. M. Hsu, S. T. Connor, Y. Xu, Q. Wang, M. McGehee, S. Fan, and Y. Cui, “Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays,” Nano Lett. 9(1), 279–282 (2009).
[CrossRef]

Hu, L.

L. Hu and G. Chen, “Analysis of optical absorption in silicon nanowire arrays for photovoltaic applications,” Nano Lett. 7(11), 3249–3252 (2007).
[CrossRef] [PubMed]

Huang, J.

B. Tian, X. Zheng, T. J. Kempa, Y. Fang, N. Yu, G. Yu, J. Huang, and C. M. Lieber, “Coaxial silicon nanowires as solar cells and nanoelectronic power sources,” Nature 449(7164), 885–889 (2007).
[CrossRef] [PubMed]

Immink, G.

S. L. Diedenhofen, G. Vecchi, R. E. Algra, A. Hartsuiker, O. L. Muskens, G. Immink, E. P. A. M. Bakkers, W. L. Vos, and J. G. Rivas, “Broad-band and omnidirectional antireflection coating based on semiconductor nanorods,” Adv. Mater. 21(9), 973–978 (2009).
[CrossRef]

Jee, S.-W.

H.-D. Um, J.-Y. Jung, H.-S. Seo, K.-T. Park, S.-W. Jee, S. A. Moiz, and J.-H. Lee, “Silicon nanowire array solar cell prepared by metal induced electroless etching with a novel processing technology,” Jpn. J. Appl. Phys. 49(4), 04DN02 (2010).
[CrossRef]

X. Li, H.-S. Seo, H.-D. Um, S.-W. Jee, Y. W. Cho, B. Yoo, and J.-H. Lee, “A periodic array of silicon pillars fabricated by photoelectrochemical etching,” Electrochim. Acta 54(27), 6978–6982 (2009).
[CrossRef]

Jung, J.-Y.

H.-D. Um, J.-Y. Jung, H.-S. Seo, K.-T. Park, S.-W. Jee, S. A. Moiz, and J.-H. Lee, “Silicon nanowire array solar cell prepared by metal induced electroless etching with a novel processing technology,” Jpn. J. Appl. Phys. 49(4), 04DN02 (2010).
[CrossRef]

Kanamori, Y.

Kayes, B. M.

B. M. Kayes, H. A. Atwater, and N. S. Lewis, “Comparison of the device physics principles of planar and radial p-n junction nanorod solar cells,” J. Appl. Phys. 97(11), 114302 (2005).
[CrossRef]

Kempa, T. J.

B. Tian, X. Zheng, T. J. Kempa, Y. Fang, N. Yu, G. Yu, J. Huang, and C. M. Lieber, “Coaxial silicon nanowires as solar cells and nanoelectronic power sources,” Nature 449(7164), 885–889 (2007).
[CrossRef] [PubMed]

Korevaar, B. A.

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

Kumar, R.

P. K. Singh, R. Kumar, M. Lal, S. N. Singh, and B. K. Das, “Effectiveness of silicon in aqueous alkaline solutions,” Sol. Energy Mater. Sol. Cells 70, 103 (2001).
[CrossRef]

Kwong, D.-L.

J. Li, H. Yu, S. M. Wong, G. Zhang, X. Sun, P. G. Lo, and D.-L. Kwong, “Design guidelines of periodic Si nanowire arrays for solar cell application,” Appl. Phys. Lett. 95, 033102 (2009).
[CrossRef]

Lal, M.

P. K. Singh, R. Kumar, M. Lal, S. N. Singh, and B. K. Das, “Effectiveness of silicon in aqueous alkaline solutions,” Sol. Energy Mater. Sol. Cells 70, 103 (2001).
[CrossRef]

LeBoeuf, S. F.

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

Lee, J.-H.

H.-D. Um, J.-Y. Jung, H.-S. Seo, K.-T. Park, S.-W. Jee, S. A. Moiz, and J.-H. Lee, “Silicon nanowire array solar cell prepared by metal induced electroless etching with a novel processing technology,” Jpn. J. Appl. Phys. 49(4), 04DN02 (2010).
[CrossRef]

X. Li, H.-S. Seo, H.-D. Um, S.-W. Jee, Y. W. Cho, B. Yoo, and J.-H. Lee, “A periodic array of silicon pillars fabricated by photoelectrochemical etching,” Electrochim. Acta 54(27), 6978–6982 (2009).
[CrossRef]

Lee, S. T.

K. Peng, Y. Xu, Y. Wu, Y. Yan, S. T. Lee, and J. Zhu, “Aligned single-crystalline Si nanowire arrays for photovoltaic applications,” Small 1(11), 1062–1067 (2005).
[CrossRef]

Lee, Y. T.

Lewis, N. S.

B. M. Kayes, H. A. Atwater, and N. S. Lewis, “Comparison of the device physics principles of planar and radial p-n junction nanorod solar cells,” J. Appl. Phys. 97(11), 114302 (2005).
[CrossRef]

Li, J.

J. Li, H. Yu, S. M. Wong, G. Zhang, X. Sun, P. G. Lo, and D.-L. Kwong, “Design guidelines of periodic Si nanowire arrays for solar cell application,” Appl. Phys. Lett. 95, 033102 (2009).
[CrossRef]

Li, X.

X. Li, H.-S. Seo, H.-D. Um, S.-W. Jee, Y. W. Cho, B. Yoo, and J.-H. Lee, “A periodic array of silicon pillars fabricated by photoelectrochemical etching,” Electrochim. Acta 54(27), 6978–6982 (2009).
[CrossRef]

Lieber, C. M.

B. Tian, X. Zheng, T. J. Kempa, Y. Fang, N. Yu, G. Yu, J. Huang, and C. M. Lieber, “Coaxial silicon nanowires as solar cells and nanoelectronic power sources,” Nature 449(7164), 885–889 (2007).
[CrossRef] [PubMed]

Lin, C.

Lo, P. G.

J. Li, H. Yu, S. M. Wong, G. Zhang, X. Sun, P. G. Lo, and D.-L. Kwong, “Design guidelines of periodic Si nanowire arrays for solar cell application,” Appl. Phys. Lett. 95, 033102 (2009).
[CrossRef]

Lu, Q.

G. Chen, J. Wu, Q. Lu, H. R. Gutierrez, Q. Xiong, M. E. Pellen, J. S. Petko, D. H. Werner, and P. C. Eklund, “Optical antenna effect in semiconducting nanowires,” Nano Lett. 8(5), 1341–1346 (2008).
[CrossRef] [PubMed]

McGehee, M.

J. Zhu, Z. Yu, G. F. Burkhard, C. M. Hsu, S. T. Connor, Y. Xu, Q. Wang, M. McGehee, S. Fan, and Y. Cui, “Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays,” Nano Lett. 9(1), 279–282 (2009).
[CrossRef]

Moiz, S. A.

H.-D. Um, J.-Y. Jung, H.-S. Seo, K.-T. Park, S.-W. Jee, S. A. Moiz, and J.-H. Lee, “Silicon nanowire array solar cell prepared by metal induced electroless etching with a novel processing technology,” Jpn. J. Appl. Phys. 49(4), 04DN02 (2010).
[CrossRef]

Muskens, O. L.

S. L. Diedenhofen, G. Vecchi, R. E. Algra, A. Hartsuiker, O. L. Muskens, G. Immink, E. P. A. M. Bakkers, W. L. Vos, and J. G. Rivas, “Broad-band and omnidirectional antireflection coating based on semiconductor nanorods,” Adv. Mater. 21(9), 973–978 (2009).
[CrossRef]

Park, K.-T.

H.-D. Um, J.-Y. Jung, H.-S. Seo, K.-T. Park, S.-W. Jee, S. A. Moiz, and J.-H. Lee, “Silicon nanowire array solar cell prepared by metal induced electroless etching with a novel processing technology,” Jpn. J. Appl. Phys. 49(4), 04DN02 (2010).
[CrossRef]

Pellen, M. E.

G. Chen, J. Wu, Q. Lu, H. R. Gutierrez, Q. Xiong, M. E. Pellen, J. S. Petko, D. H. Werner, and P. C. Eklund, “Optical antenna effect in semiconducting nanowires,” Nano Lett. 8(5), 1341–1346 (2008).
[CrossRef] [PubMed]

Peng, K.

K. Peng, Y. Xu, Y. Wu, Y. Yan, S. T. Lee, and J. Zhu, “Aligned single-crystalline Si nanowire arrays for photovoltaic applications,” Small 1(11), 1062–1067 (2005).
[CrossRef]

Peng, K. Q.

K. Q. Peng, Y. Wu, H. Fang, X. Zhong, Y. Xu, and J. Zhu, “Uniform, axial-orientation alignment of one-dimensional single-crystal silicon nanostructure arrays,” Angew. Chem. Int. Ed. Engl. 44(18), 2737–2742 (2005).
[CrossRef] [PubMed]

Petko, J. S.

G. Chen, J. Wu, Q. Lu, H. R. Gutierrez, Q. Xiong, M. E. Pellen, J. S. Petko, D. H. Werner, and P. C. Eklund, “Optical antenna effect in semiconducting nanowires,” Nano Lett. 8(5), 1341–1346 (2008).
[CrossRef] [PubMed]

Pietrzykowski, M.

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

Plentz, J.

V. Sivakov, G. Andrä, A. Gawlik, A. Berger, J. Plentz, F. Falk, and S. H. Christiansen, “Silicon nanowire-based solar cells on glass: synthesis, optical properties, and cell parameters,” Nano Lett. 9(4), 1549–1554 (2009).
[CrossRef] [PubMed]

Povinelli, M. L.

Rand, J.

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

Rapol, U.

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

Rivas, J. G.

S. L. Diedenhofen, G. Vecchi, R. E. Algra, A. Hartsuiker, O. L. Muskens, G. Immink, E. P. A. M. Bakkers, W. L. Vos, and J. G. Rivas, “Broad-band and omnidirectional antireflection coating based on semiconductor nanorods,” Adv. Mater. 21(9), 973–978 (2009).
[CrossRef]

Sasaki, M.

Seo, H.-S.

H.-D. Um, J.-Y. Jung, H.-S. Seo, K.-T. Park, S.-W. Jee, S. A. Moiz, and J.-H. Lee, “Silicon nanowire array solar cell prepared by metal induced electroless etching with a novel processing technology,” Jpn. J. Appl. Phys. 49(4), 04DN02 (2010).
[CrossRef]

X. Li, H.-S. Seo, H.-D. Um, S.-W. Jee, Y. W. Cho, B. Yoo, and J.-H. Lee, “A periodic array of silicon pillars fabricated by photoelectrochemical etching,” Electrochim. Acta 54(27), 6978–6982 (2009).
[CrossRef]

Shih, M. Y.

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

Singh, P. K.

P. K. Singh, R. Kumar, M. Lal, S. N. Singh, and B. K. Das, “Effectiveness of silicon in aqueous alkaline solutions,” Sol. Energy Mater. Sol. Cells 70, 103 (2001).
[CrossRef]

Singh, S. N.

P. K. Singh, R. Kumar, M. Lal, S. N. Singh, and B. K. Das, “Effectiveness of silicon in aqueous alkaline solutions,” Sol. Energy Mater. Sol. Cells 70, 103 (2001).
[CrossRef]

Sivakov, V.

V. Sivakov, G. Andrä, A. Gawlik, A. Berger, J. Plentz, F. Falk, and S. H. Christiansen, “Silicon nanowire-based solar cells on glass: synthesis, optical properties, and cell parameters,” Nano Lett. 9(4), 1549–1554 (2009).
[CrossRef] [PubMed]

Song, Y. M.

Sulima, O.

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

Sun, X.

J. Li, H. Yu, S. M. Wong, G. Zhang, X. Sun, P. G. Lo, and D.-L. Kwong, “Design guidelines of periodic Si nanowire arrays for solar cell application,” Appl. Phys. Lett. 95, 033102 (2009).
[CrossRef]

Tian, B.

B. Tian, X. Zheng, T. J. Kempa, Y. Fang, N. Yu, G. Yu, J. Huang, and C. M. Lieber, “Coaxial silicon nanowires as solar cells and nanoelectronic power sources,” Nature 449(7164), 885–889 (2007).
[CrossRef] [PubMed]

Tsakalakos, L.

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

Um, H.-D.

H.-D. Um, J.-Y. Jung, H.-S. Seo, K.-T. Park, S.-W. Jee, S. A. Moiz, and J.-H. Lee, “Silicon nanowire array solar cell prepared by metal induced electroless etching with a novel processing technology,” Jpn. J. Appl. Phys. 49(4), 04DN02 (2010).
[CrossRef]

X. Li, H.-S. Seo, H.-D. Um, S.-W. Jee, Y. W. Cho, B. Yoo, and J.-H. Lee, “A periodic array of silicon pillars fabricated by photoelectrochemical etching,” Electrochim. Acta 54(27), 6978–6982 (2009).
[CrossRef]

Vecchi, G.

S. L. Diedenhofen, G. Vecchi, R. E. Algra, A. Hartsuiker, O. L. Muskens, G. Immink, E. P. A. M. Bakkers, W. L. Vos, and J. G. Rivas, “Broad-band and omnidirectional antireflection coating based on semiconductor nanorods,” Adv. Mater. 21(9), 973–978 (2009).
[CrossRef]

Vos, W. L.

S. L. Diedenhofen, G. Vecchi, R. E. Algra, A. Hartsuiker, O. L. Muskens, G. Immink, E. P. A. M. Bakkers, W. L. Vos, and J. G. Rivas, “Broad-band and omnidirectional antireflection coating based on semiconductor nanorods,” Adv. Mater. 21(9), 973–978 (2009).
[CrossRef]

Wang, Q.

J. Zhu, Z. Yu, G. F. Burkhard, C. M. Hsu, S. T. Connor, Y. Xu, Q. Wang, M. McGehee, S. Fan, and Y. Cui, “Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays,” Nano Lett. 9(1), 279–282 (2009).
[CrossRef]

Werner, D. H.

G. Chen, J. Wu, Q. Lu, H. R. Gutierrez, Q. Xiong, M. E. Pellen, J. S. Petko, D. H. Werner, and P. C. Eklund, “Optical antenna effect in semiconducting nanowires,” Nano Lett. 8(5), 1341–1346 (2008).
[CrossRef] [PubMed]

Wong, S. M.

J. Li, H. Yu, S. M. Wong, G. Zhang, X. Sun, P. G. Lo, and D.-L. Kwong, “Design guidelines of periodic Si nanowire arrays for solar cell application,” Appl. Phys. Lett. 95, 033102 (2009).
[CrossRef]

Wu, J.

G. Chen, J. Wu, Q. Lu, H. R. Gutierrez, Q. Xiong, M. E. Pellen, J. S. Petko, D. H. Werner, and P. C. Eklund, “Optical antenna effect in semiconducting nanowires,” Nano Lett. 8(5), 1341–1346 (2008).
[CrossRef] [PubMed]

Wu, Y.

K. Peng, Y. Xu, Y. Wu, Y. Yan, S. T. Lee, and J. Zhu, “Aligned single-crystalline Si nanowire arrays for photovoltaic applications,” Small 1(11), 1062–1067 (2005).
[CrossRef]

K. Q. Peng, Y. Wu, H. Fang, X. Zhong, Y. Xu, and J. Zhu, “Uniform, axial-orientation alignment of one-dimensional single-crystal silicon nanostructure arrays,” Angew. Chem. Int. Ed. Engl. 44(18), 2737–2742 (2005).
[CrossRef] [PubMed]

Xiong, Q.

G. Chen, J. Wu, Q. Lu, H. R. Gutierrez, Q. Xiong, M. E. Pellen, J. S. Petko, D. H. Werner, and P. C. Eklund, “Optical antenna effect in semiconducting nanowires,” Nano Lett. 8(5), 1341–1346 (2008).
[CrossRef] [PubMed]

Xu, Y.

J. Zhu, Z. Yu, G. F. Burkhard, C. M. Hsu, S. T. Connor, Y. Xu, Q. Wang, M. McGehee, S. Fan, and Y. Cui, “Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays,” Nano Lett. 9(1), 279–282 (2009).
[CrossRef]

K. Peng, Y. Xu, Y. Wu, Y. Yan, S. T. Lee, and J. Zhu, “Aligned single-crystalline Si nanowire arrays for photovoltaic applications,” Small 1(11), 1062–1067 (2005).
[CrossRef]

K. Q. Peng, Y. Wu, H. Fang, X. Zhong, Y. Xu, and J. Zhu, “Uniform, axial-orientation alignment of one-dimensional single-crystal silicon nanostructure arrays,” Angew. Chem. Int. Ed. Engl. 44(18), 2737–2742 (2005).
[CrossRef] [PubMed]

Yan, Y.

K. Peng, Y. Xu, Y. Wu, Y. Yan, S. T. Lee, and J. Zhu, “Aligned single-crystalline Si nanowire arrays for photovoltaic applications,” Small 1(11), 1062–1067 (2005).
[CrossRef]

Yang, P. D.

E. C. Garnett and P. D. Yang, “Silicon nanowire radial p-n junction solar cells,” J. Am. Chem. Soc. 130(29), 9224–9225 (2008).
[CrossRef] [PubMed]

Yoo, B.

X. Li, H.-S. Seo, H.-D. Um, S.-W. Jee, Y. W. Cho, B. Yoo, and J.-H. Lee, “A periodic array of silicon pillars fabricated by photoelectrochemical etching,” Electrochim. Acta 54(27), 6978–6982 (2009).
[CrossRef]

Yu, G.

B. Tian, X. Zheng, T. J. Kempa, Y. Fang, N. Yu, G. Yu, J. Huang, and C. M. Lieber, “Coaxial silicon nanowires as solar cells and nanoelectronic power sources,” Nature 449(7164), 885–889 (2007).
[CrossRef] [PubMed]

Yu, H.

J. Li, H. Yu, S. M. Wong, G. Zhang, X. Sun, P. G. Lo, and D.-L. Kwong, “Design guidelines of periodic Si nanowire arrays for solar cell application,” Appl. Phys. Lett. 95, 033102 (2009).
[CrossRef]

Yu, J. S.

Yu, N.

B. Tian, X. Zheng, T. J. Kempa, Y. Fang, N. Yu, G. Yu, J. Huang, and C. M. Lieber, “Coaxial silicon nanowires as solar cells and nanoelectronic power sources,” Nature 449(7164), 885–889 (2007).
[CrossRef] [PubMed]

Yu, Z.

J. Zhu, Z. Yu, G. F. Burkhard, C. M. Hsu, S. T. Connor, Y. Xu, Q. Wang, M. McGehee, S. Fan, and Y. Cui, “Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays,” Nano Lett. 9(1), 279–282 (2009).
[CrossRef]

Zhang, G.

J. Li, H. Yu, S. M. Wong, G. Zhang, X. Sun, P. G. Lo, and D.-L. Kwong, “Design guidelines of periodic Si nanowire arrays for solar cell application,” Appl. Phys. Lett. 95, 033102 (2009).
[CrossRef]

Zheng, X.

B. Tian, X. Zheng, T. J. Kempa, Y. Fang, N. Yu, G. Yu, J. Huang, and C. M. Lieber, “Coaxial silicon nanowires as solar cells and nanoelectronic power sources,” Nature 449(7164), 885–889 (2007).
[CrossRef] [PubMed]

Zhong, X.

K. Q. Peng, Y. Wu, H. Fang, X. Zhong, Y. Xu, and J. Zhu, “Uniform, axial-orientation alignment of one-dimensional single-crystal silicon nanostructure arrays,” Angew. Chem. Int. Ed. Engl. 44(18), 2737–2742 (2005).
[CrossRef] [PubMed]

Zhu, J.

J. Zhu, Z. Yu, G. F. Burkhard, C. M. Hsu, S. T. Connor, Y. Xu, Q. Wang, M. McGehee, S. Fan, and Y. Cui, “Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays,” Nano Lett. 9(1), 279–282 (2009).
[CrossRef]

K. Peng, Y. Xu, Y. Wu, Y. Yan, S. T. Lee, and J. Zhu, “Aligned single-crystalline Si nanowire arrays for photovoltaic applications,” Small 1(11), 1062–1067 (2005).
[CrossRef]

K. Q. Peng, Y. Wu, H. Fang, X. Zhong, Y. Xu, and J. Zhu, “Uniform, axial-orientation alignment of one-dimensional single-crystal silicon nanostructure arrays,” Angew. Chem. Int. Ed. Engl. 44(18), 2737–2742 (2005).
[CrossRef] [PubMed]

Adv. Mater. (1)

S. L. Diedenhofen, G. Vecchi, R. E. Algra, A. Hartsuiker, O. L. Muskens, G. Immink, E. P. A. M. Bakkers, W. L. Vos, and J. G. Rivas, “Broad-band and omnidirectional antireflection coating based on semiconductor nanorods,” Adv. Mater. 21(9), 973–978 (2009).
[CrossRef]

Angew. Chem. Int. Ed. Engl. (1)

K. Q. Peng, Y. Wu, H. Fang, X. Zhong, Y. Xu, and J. Zhu, “Uniform, axial-orientation alignment of one-dimensional single-crystal silicon nanostructure arrays,” Angew. Chem. Int. Ed. Engl. 44(18), 2737–2742 (2005).
[CrossRef] [PubMed]

Appl. Phys. Lett. (1)

J. Li, H. Yu, S. M. Wong, G. Zhang, X. Sun, P. G. Lo, and D.-L. Kwong, “Design guidelines of periodic Si nanowire arrays for solar cell application,” Appl. Phys. Lett. 95, 033102 (2009).
[CrossRef]

Electrochim. Acta (1)

X. Li, H.-S. Seo, H.-D. Um, S.-W. Jee, Y. W. Cho, B. Yoo, and J.-H. Lee, “A periodic array of silicon pillars fabricated by photoelectrochemical etching,” Electrochim. Acta 54(27), 6978–6982 (2009).
[CrossRef]

J. Am. Chem. Soc. (1)

E. C. Garnett and P. D. Yang, “Silicon nanowire radial p-n junction solar cells,” J. Am. Chem. Soc. 130(29), 9224–9225 (2008).
[CrossRef] [PubMed]

J. Appl. Phys. (1)

B. M. Kayes, H. A. Atwater, and N. S. Lewis, “Comparison of the device physics principles of planar and radial p-n junction nanorod solar cells,” J. Appl. Phys. 97(11), 114302 (2005).
[CrossRef]

J. Nanophotonics (1)

L. Tsakalakos, J. Balch, J. Fronheiser, M. Y. Shih, S. F. LeBoeuf, M. Pietrzykowski, P. J. Codella, B. A. Korevaar, O. Sulima, J. Rand, A. Davuluru, and U. Rapol, “Strong broadband optical absorption in silicon nanowire films,” J. Nanophotonics 1(1), 013552 (2007).
[CrossRef]

Jpn. J. Appl. Phys. (1)

H.-D. Um, J.-Y. Jung, H.-S. Seo, K.-T. Park, S.-W. Jee, S. A. Moiz, and J.-H. Lee, “Silicon nanowire array solar cell prepared by metal induced electroless etching with a novel processing technology,” Jpn. J. Appl. Phys. 49(4), 04DN02 (2010).
[CrossRef]

Nano Lett. (4)

V. Sivakov, G. Andrä, A. Gawlik, A. Berger, J. Plentz, F. Falk, and S. H. Christiansen, “Silicon nanowire-based solar cells on glass: synthesis, optical properties, and cell parameters,” Nano Lett. 9(4), 1549–1554 (2009).
[CrossRef] [PubMed]

G. Chen, J. Wu, Q. Lu, H. R. Gutierrez, Q. Xiong, M. E. Pellen, J. S. Petko, D. H. Werner, and P. C. Eklund, “Optical antenna effect in semiconducting nanowires,” Nano Lett. 8(5), 1341–1346 (2008).
[CrossRef] [PubMed]

J. Zhu, Z. Yu, G. F. Burkhard, C. M. Hsu, S. T. Connor, Y. Xu, Q. Wang, M. McGehee, S. Fan, and Y. Cui, “Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays,” Nano Lett. 9(1), 279–282 (2009).
[CrossRef]

L. Hu and G. Chen, “Analysis of optical absorption in silicon nanowire arrays for photovoltaic applications,” Nano Lett. 7(11), 3249–3252 (2007).
[CrossRef] [PubMed]

Nature (1)

B. Tian, X. Zheng, T. J. Kempa, Y. Fang, N. Yu, G. Yu, J. Huang, and C. M. Lieber, “Coaxial silicon nanowires as solar cells and nanoelectronic power sources,” Nature 449(7164), 885–889 (2007).
[CrossRef] [PubMed]

Opt. Express (1)

Opt. Lett. (2)

Small (1)

K. Peng, Y. Xu, Y. Wu, Y. Yan, S. T. Lee, and J. Zhu, “Aligned single-crystalline Si nanowire arrays for photovoltaic applications,” Small 1(11), 1062–1067 (2005).
[CrossRef]

Sol. Energy Mater. Sol. Cells (1)

P. K. Singh, R. Kumar, M. Lal, S. N. Singh, and B. K. Das, “Effectiveness of silicon in aqueous alkaline solutions,” Sol. Energy Mater. Sol. Cells 70, 103 (2001).
[CrossRef]

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Figures (4)

Fig. 1
Fig. 1

(a) Schematic illustrations showing the fabrication procedures for bunched and tapered SiNWs. (b) Conceptual schematic for explaining how the SiNWs can be easily tapered at their top-ends using KOH post-etching. Bottom SEM images show the 30°-tilted-view corresponding to each KOH etching time step (0, 30, 60, 120 s from left to right, respectively). All scale bars are 1 μm.

Fig. 2
Fig. 2

(a) Cross-sectional SEM images showing the SiNW array after metal-assisted electroless etching. Scale bar is 10 μm. 30°-tilted SEM images also show the morphological change of the SiNW tips according to the post-etching time of KOH: (b) 0 s, (c) 30 s, (d) 60 s, (e) 120 s, and (f) 240 s. Scale bars in (b)−(f) are 5 μm.

Fig. 3
Fig. 3

(a) Optical reflectance spectra of a Si wafer, bunched SiNWs, and various tapered samples, (b) reflectance spectra shown in a different scale than (a) for the tapered samples. Schematic illustrations showing the relevance between the wire morphology and the effective refractive index profile across the air-to-wire axis: (c) air-to-silicon wafer, (d) air-to-bunched NWs, (e) air-to-tapered NWs (60 s KOH dip), (f) air-to-tapered NWs (120 s dip). Black arrows denote the mismatch regions in the effective refractive indexes.

Fig. 4
Fig. 4

Typical photovoltaic I-V curves for bunched and tapered SiNWs (60 s KOH etching). Upper left inset: table comparing the representative photovoltaic parameters, Lower right inset: schematic illustration showing the top-contact structure.

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