Abstract

We demonstrate enhanced photocarrier generation using photonic nanostructures fabricated by a wet etching technique with vertically aligned quantum dots (QDs). Using photoluminescence excitation spectroscopy, we found that the photocarrier generation in Ge/Si QDs placed close to the surface is enhanced below the band gap energy of crystalline silicon. The enhancement is explained by light trapping owing to the photonic nanostructures. Electromagnetic wave simulations indicate that the photonic nanostructure with a subwavelength size will be available to light trapping for efficient photocarrier generation by increasing their dip depth.

© 2014 Optical Society of America

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2013 (6)

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

P. Krogstrup, H. I. Jørgensen, M. Heiss, O. Demichel, J. V. Holm, M. Aagesen, J. Nygard, and A. Fontcuberta i Morral, “Single-nanowire solar cells beyond the Shockley–Queisser limit,” Nat. Photonics 7(4), 306–310 (2013).
[CrossRef]

F. Pratesi, M. Burresi, F. Riboli, K. Vynck, and D. S. Wiersma, “Disordered photonic structures for light harvesting in solar cells,” Opt. Express 21(S3Suppl 3), A460–A468 (2013).
[CrossRef] [PubMed]

M. Burresi, F. Pratesi, K. Vynck, M. Prasciolu, M. Tormen, and D. S. Wiersma, “Two-dimensional disorder for broadband, omnidirectional and polarization-insensitive absorption,” Opt. Express 21(S2Suppl 2), A268–A275 (2013).
[CrossRef] [PubMed]

Y. Hoshi, W. Pan, T. Kiguchi, K. Ooi, T. Tayagaki, and N. Usami, “Control of dip shape in photonic nanostructures by maskless wet-etching process and its impact on optical properties,” Jpn. J. Appl. Phys. 52(8R), 080202 (2013).
[CrossRef]

T. Tayagaki, Y. Hoshi, and N. Usami, “Investigation of the open-circuit voltage in solar cells doped with quantum dots,” Sci Rep 3, 2703 (2013).
[CrossRef] [PubMed]

2012 (7)

T. Tayagaki, N. Usami, W. Pan, Y. Hoshi, K. Ooi, and Y. Kanemitsu, “Enhanced carrier extraction from Ge quantum dots in Si solar cells under strong photoexcitation,” Appl. Phys. Lett. 101(13), 133905 (2012).
[CrossRef]

N. Usami, W. Pan, T. Tayagaki, S. T. Chu, J. Li, T. Feng, Y. Hoshi, and T. Kiguchi, “Simultaneous enhanced photon capture and carrier generation in Si solar cells using Ge quantum dot photonic nanocrystals,” Nanotechnology 23(18), 185401 (2012).
[CrossRef] [PubMed]

T. Tayagaki, K. Ueda, S. Fukatsu, and Y. Kanemitsu, “Recombination dynamics of high-density photocarriers in type-II Ge/Si quantum dots,” J. Phys. Soc. Jpn. 81(6), 064712 (2012).
[CrossRef]

K. Vynck, M. Burresi, F. Riboli, and D. S. Wiersma, “Photon management in two-dimensional disordered media,” Nat. Mater. 11(12), 1017–1022 (2012).
[PubMed]

M. A. Green and S. Pillai, “Harnessing plasmonics for solar cells,” Nat. Photonics 6(3), 130–132 (2012).
[CrossRef]

A. Niv, M. Gharghi, C. Gladden, O. D. Miller, and X. Zhang, “Near-field electromagnetic theory for thin solar cells,” Phys. Rev. Lett. 109(13), 138701 (2012).
[CrossRef] [PubMed]

A. Oskooi, P. A. Favuzzi, Y. Tanaka, H. Shigeta, Y. Kawakami, and S. Noda, “Partially disordered photonic-crystal thin films for enhanced and robust photovoltaics,” Appl. Phys. Lett. 100(18), 181110 (2012).
[CrossRef]

2011 (2)

J. Bhattacharya, N. Chakravarty, S. Pattnaik, W. Dennis Slafer, R. Biswas, and V. L. Dalal, “A photonic-plasmonic structure for enhancing light absorption in thin film solar cells,” Appl. Phys. Lett. 99(13), 131114 (2011).
[CrossRef]

E. T. Yu and J. van de Lagemaat, “Photon management for photovoltaics,” MRS Bull. 36(06), 424–428 (2011).
[CrossRef]

2010 (4)

V. E. Ferry, M. A. Verschuuren, H. B. T. Li, E. Verhagen, R. J. Walters, R. E. I. Schropp, H. A. Atwater, and A. Polman, “Light trapping in ultrathin plasmonic solar cells,” Opt. Express 18(S2Suppl 2), A237–A245 (2010).
[CrossRef] [PubMed]

Z. Yu, A. Raman, and S. Fan, “Fundamental limit of nanophotonic light trapping in solar cells,” Proc. Natl. Acad. Sci. U.S.A. 107(41), 17491–17496 (2010).
[CrossRef] [PubMed]

H. A. Atwater and A. Polman, “Plasmonics for improved photovoltaic devices,” Nat. Mater. 9(3), 205–213 (2010).
[CrossRef] [PubMed]

M. D. Kelzenberg, S. W. Boettcher, J. A. Petykiewicz, D. B. Turner-Evans, M. C. Putnam, E. L. Warren, J. M. Spurgeon, R. M. Briggs, N. S. Lewis, and H. A. Atwater, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” Nat. Mater. 9(3), 239–244 (2010).
[PubMed]

2009 (1)

H.-C. Yuan, V. E. Yost, M. R. Page, P. Stradins, D. L. Meier, and H. M. Branz, “Efficient black silicon solar cell with a density-graded nanoporous surface: optical properties, performance limitations, and design rules,” Appl. Phys. Lett. 95(12), 123501 (2009).
[CrossRef]

2007 (1)

J.-Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S.-Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

2006 (1)

H. Sai, H. Fujii, K. Arafune, Y. Ohshita, M. Yamaguchi, Y. Kanamori, and H. Yugami, “Antireflective subwavelength structures on crystalline Si fabricated using directly formed anodic porous alumina masks,” Appl. Phys. Lett. 88(20), 201116 (2006).
[CrossRef]

2005 (1)

Z. Zhong, G. Katsaros, M. Stoffel, G. Costantini, K. Kern, O. G. Schmidt, N. Y. Jin-Phillipp, and G. Bauer, “Periodic pillar structures by Si etching of multilayer GeSi/Si islands,” Appl. Phys. Lett. 87(26), 263102 (2005).
[CrossRef]

2003 (1)

A. Alguno, N. Usami, T. Ujihara, K. Fujiwara, G. Sazaki, K. Nakajima, and Y. Shiraki, “Enhanced quantum efficiency of solar cells with self-assembled Ge dots stacked in multilayer structure,” Appl. Phys. Lett. 83(6), 1258–1260 (2003).
[CrossRef]

1998 (1)

L. Stalmans, J. Poortmans, H. Bender, M. Caymax, K. Said, E. Vazsonyi, J. Nijs, and R. Mertens, “Porous silicon in crystalline silicon solar cells: a review and the effect on the internal quantum efficiency,” Prog. Photovolt. Res. Appl. 6(4), 233–246 (1998).
[CrossRef]

1996 (1)

J. Zhao, A. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, “24% efficient perl silicon solar cell: recent improvements in high efficiency silicon cell research,” Sol. Energy Mater. Sol. Cells 41–42, 87–99 (1996).
[CrossRef]

1995 (1)

H. Sunamura, N. Usami, Y. Shiraki, and S. Fukatsu, “Island formation during growth of Ge on Si(100): a study using photoluminescence spectroscopy,” Appl. Phys. Lett. 66(22), 3024–3026 (1995).
[CrossRef]

1982 (1)

1955 (1)

W. C. Dash and R. Newman, “Optical absorption in single-crystal germanium and silicon at 77°K and 300°K,” Phys. Rev. 99(4), 1151–1155 (1955).
[CrossRef]

Aagesen, M.

P. Krogstrup, H. I. Jørgensen, M. Heiss, O. Demichel, J. V. Holm, M. Aagesen, J. Nygard, and A. Fontcuberta i Morral, “Single-nanowire solar cells beyond the Shockley–Queisser limit,” Nat. Photonics 7(4), 306–310 (2013).
[CrossRef]

Åberg, I.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Alguno, A.

A. Alguno, N. Usami, T. Ujihara, K. Fujiwara, G. Sazaki, K. Nakajima, and Y. Shiraki, “Enhanced quantum efficiency of solar cells with self-assembled Ge dots stacked in multilayer structure,” Appl. Phys. Lett. 83(6), 1258–1260 (2003).
[CrossRef]

Altermatt, P. P.

J. Zhao, A. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, “24% efficient perl silicon solar cell: recent improvements in high efficiency silicon cell research,” Sol. Energy Mater. Sol. Cells 41–42, 87–99 (1996).
[CrossRef]

Anttu, N.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Arafune, K.

H. Sai, H. Fujii, K. Arafune, Y. Ohshita, M. Yamaguchi, Y. Kanamori, and H. Yugami, “Antireflective subwavelength structures on crystalline Si fabricated using directly formed anodic porous alumina masks,” Appl. Phys. Lett. 88(20), 201116 (2006).
[CrossRef]

Asoli, D.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Atwater, H. A.

H. A. Atwater and A. Polman, “Plasmonics for improved photovoltaic devices,” Nat. Mater. 9(3), 205–213 (2010).
[CrossRef] [PubMed]

M. D. Kelzenberg, S. W. Boettcher, J. A. Petykiewicz, D. B. Turner-Evans, M. C. Putnam, E. L. Warren, J. M. Spurgeon, R. M. Briggs, N. S. Lewis, and H. A. Atwater, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” Nat. Mater. 9(3), 239–244 (2010).
[PubMed]

V. E. Ferry, M. A. Verschuuren, H. B. T. Li, E. Verhagen, R. J. Walters, R. E. I. Schropp, H. A. Atwater, and A. Polman, “Light trapping in ultrathin plasmonic solar cells,” Opt. Express 18(S2Suppl 2), A237–A245 (2010).
[CrossRef] [PubMed]

Bauer, G.

Z. Zhong, G. Katsaros, M. Stoffel, G. Costantini, K. Kern, O. G. Schmidt, N. Y. Jin-Phillipp, and G. Bauer, “Periodic pillar structures by Si etching of multilayer GeSi/Si islands,” Appl. Phys. Lett. 87(26), 263102 (2005).
[CrossRef]

Bender, H.

L. Stalmans, J. Poortmans, H. Bender, M. Caymax, K. Said, E. Vazsonyi, J. Nijs, and R. Mertens, “Porous silicon in crystalline silicon solar cells: a review and the effect on the internal quantum efficiency,” Prog. Photovolt. Res. Appl. 6(4), 233–246 (1998).
[CrossRef]

Bhattacharya, J.

J. Bhattacharya, N. Chakravarty, S. Pattnaik, W. Dennis Slafer, R. Biswas, and V. L. Dalal, “A photonic-plasmonic structure for enhancing light absorption in thin film solar cells,” Appl. Phys. Lett. 99(13), 131114 (2011).
[CrossRef]

Biswas, R.

J. Bhattacharya, N. Chakravarty, S. Pattnaik, W. Dennis Slafer, R. Biswas, and V. L. Dalal, “A photonic-plasmonic structure for enhancing light absorption in thin film solar cells,” Appl. Phys. Lett. 99(13), 131114 (2011).
[CrossRef]

Boettcher, S. W.

M. D. Kelzenberg, S. W. Boettcher, J. A. Petykiewicz, D. B. Turner-Evans, M. C. Putnam, E. L. Warren, J. M. Spurgeon, R. M. Briggs, N. S. Lewis, and H. A. Atwater, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” Nat. Mater. 9(3), 239–244 (2010).
[PubMed]

Borgström, M. T.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Branz, H. M.

H.-C. Yuan, V. E. Yost, M. R. Page, P. Stradins, D. L. Meier, and H. M. Branz, “Efficient black silicon solar cell with a density-graded nanoporous surface: optical properties, performance limitations, and design rules,” Appl. Phys. Lett. 95(12), 123501 (2009).
[CrossRef]

Briggs, R. M.

M. D. Kelzenberg, S. W. Boettcher, J. A. Petykiewicz, D. B. Turner-Evans, M. C. Putnam, E. L. Warren, J. M. Spurgeon, R. M. Briggs, N. S. Lewis, and H. A. Atwater, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” Nat. Mater. 9(3), 239–244 (2010).
[PubMed]

Burresi, M.

Caymax, M.

L. Stalmans, J. Poortmans, H. Bender, M. Caymax, K. Said, E. Vazsonyi, J. Nijs, and R. Mertens, “Porous silicon in crystalline silicon solar cells: a review and the effect on the internal quantum efficiency,” Prog. Photovolt. Res. Appl. 6(4), 233–246 (1998).
[CrossRef]

Chakravarty, N.

J. Bhattacharya, N. Chakravarty, S. Pattnaik, W. Dennis Slafer, R. Biswas, and V. L. Dalal, “A photonic-plasmonic structure for enhancing light absorption in thin film solar cells,” Appl. Phys. Lett. 99(13), 131114 (2011).
[CrossRef]

Chen, M.

J.-Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S.-Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Chu, S. T.

N. Usami, W. Pan, T. Tayagaki, S. T. Chu, J. Li, T. Feng, Y. Hoshi, and T. Kiguchi, “Simultaneous enhanced photon capture and carrier generation in Si solar cells using Ge quantum dot photonic nanocrystals,” Nanotechnology 23(18), 185401 (2012).
[CrossRef] [PubMed]

Costantini, G.

Z. Zhong, G. Katsaros, M. Stoffel, G. Costantini, K. Kern, O. G. Schmidt, N. Y. Jin-Phillipp, and G. Bauer, “Periodic pillar structures by Si etching of multilayer GeSi/Si islands,” Appl. Phys. Lett. 87(26), 263102 (2005).
[CrossRef]

Dalal, V. L.

J. Bhattacharya, N. Chakravarty, S. Pattnaik, W. Dennis Slafer, R. Biswas, and V. L. Dalal, “A photonic-plasmonic structure for enhancing light absorption in thin film solar cells,” Appl. Phys. Lett. 99(13), 131114 (2011).
[CrossRef]

Dash, W. C.

W. C. Dash and R. Newman, “Optical absorption in single-crystal germanium and silicon at 77°K and 300°K,” Phys. Rev. 99(4), 1151–1155 (1955).
[CrossRef]

Demichel, O.

P. Krogstrup, H. I. Jørgensen, M. Heiss, O. Demichel, J. V. Holm, M. Aagesen, J. Nygard, and A. Fontcuberta i Morral, “Single-nanowire solar cells beyond the Shockley–Queisser limit,” Nat. Photonics 7(4), 306–310 (2013).
[CrossRef]

Dennis Slafer, W.

J. Bhattacharya, N. Chakravarty, S. Pattnaik, W. Dennis Slafer, R. Biswas, and V. L. Dalal, “A photonic-plasmonic structure for enhancing light absorption in thin film solar cells,” Appl. Phys. Lett. 99(13), 131114 (2011).
[CrossRef]

Deppert, K.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Dimroth, F.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Fan, S.

Z. Yu, A. Raman, and S. Fan, “Fundamental limit of nanophotonic light trapping in solar cells,” Proc. Natl. Acad. Sci. U.S.A. 107(41), 17491–17496 (2010).
[CrossRef] [PubMed]

Favuzzi, P. A.

A. Oskooi, P. A. Favuzzi, Y. Tanaka, H. Shigeta, Y. Kawakami, and S. Noda, “Partially disordered photonic-crystal thin films for enhanced and robust photovoltaics,” Appl. Phys. Lett. 100(18), 181110 (2012).
[CrossRef]

Feng, T.

N. Usami, W. Pan, T. Tayagaki, S. T. Chu, J. Li, T. Feng, Y. Hoshi, and T. Kiguchi, “Simultaneous enhanced photon capture and carrier generation in Si solar cells using Ge quantum dot photonic nanocrystals,” Nanotechnology 23(18), 185401 (2012).
[CrossRef] [PubMed]

Ferry, V. E.

Fontcuberta i Morral, A.

P. Krogstrup, H. I. Jørgensen, M. Heiss, O. Demichel, J. V. Holm, M. Aagesen, J. Nygard, and A. Fontcuberta i Morral, “Single-nanowire solar cells beyond the Shockley–Queisser limit,” Nat. Photonics 7(4), 306–310 (2013).
[CrossRef]

Fujii, H.

H. Sai, H. Fujii, K. Arafune, Y. Ohshita, M. Yamaguchi, Y. Kanamori, and H. Yugami, “Antireflective subwavelength structures on crystalline Si fabricated using directly formed anodic porous alumina masks,” Appl. Phys. Lett. 88(20), 201116 (2006).
[CrossRef]

Fujiwara, K.

A. Alguno, N. Usami, T. Ujihara, K. Fujiwara, G. Sazaki, K. Nakajima, and Y. Shiraki, “Enhanced quantum efficiency of solar cells with self-assembled Ge dots stacked in multilayer structure,” Appl. Phys. Lett. 83(6), 1258–1260 (2003).
[CrossRef]

Fukatsu, S.

T. Tayagaki, K. Ueda, S. Fukatsu, and Y. Kanemitsu, “Recombination dynamics of high-density photocarriers in type-II Ge/Si quantum dots,” J. Phys. Soc. Jpn. 81(6), 064712 (2012).
[CrossRef]

H. Sunamura, N. Usami, Y. Shiraki, and S. Fukatsu, “Island formation during growth of Ge on Si(100): a study using photoluminescence spectroscopy,” Appl. Phys. Lett. 66(22), 3024–3026 (1995).
[CrossRef]

Fuss-Kailuweit, P.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

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A. Niv, M. Gharghi, C. Gladden, O. D. Miller, and X. Zhang, “Near-field electromagnetic theory for thin solar cells,” Phys. Rev. Lett. 109(13), 138701 (2012).
[CrossRef] [PubMed]

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A. Niv, M. Gharghi, C. Gladden, O. D. Miller, and X. Zhang, “Near-field electromagnetic theory for thin solar cells,” Phys. Rev. Lett. 109(13), 138701 (2012).
[CrossRef] [PubMed]

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M. A. Green and S. Pillai, “Harnessing plasmonics for solar cells,” Nat. Photonics 6(3), 130–132 (2012).
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J. Zhao, A. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, “24% efficient perl silicon solar cell: recent improvements in high efficiency silicon cell research,” Sol. Energy Mater. Sol. Cells 41–42, 87–99 (1996).
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P. Krogstrup, H. I. Jørgensen, M. Heiss, O. Demichel, J. V. Holm, M. Aagesen, J. Nygard, and A. Fontcuberta i Morral, “Single-nanowire solar cells beyond the Shockley–Queisser limit,” Nat. Photonics 7(4), 306–310 (2013).
[CrossRef]

Holm, J. V.

P. Krogstrup, H. I. Jørgensen, M. Heiss, O. Demichel, J. V. Holm, M. Aagesen, J. Nygard, and A. Fontcuberta i Morral, “Single-nanowire solar cells beyond the Shockley–Queisser limit,” Nat. Photonics 7(4), 306–310 (2013).
[CrossRef]

Hoshi, Y.

T. Tayagaki, Y. Hoshi, and N. Usami, “Investigation of the open-circuit voltage in solar cells doped with quantum dots,” Sci Rep 3, 2703 (2013).
[CrossRef] [PubMed]

Y. Hoshi, W. Pan, T. Kiguchi, K. Ooi, T. Tayagaki, and N. Usami, “Control of dip shape in photonic nanostructures by maskless wet-etching process and its impact on optical properties,” Jpn. J. Appl. Phys. 52(8R), 080202 (2013).
[CrossRef]

N. Usami, W. Pan, T. Tayagaki, S. T. Chu, J. Li, T. Feng, Y. Hoshi, and T. Kiguchi, “Simultaneous enhanced photon capture and carrier generation in Si solar cells using Ge quantum dot photonic nanocrystals,” Nanotechnology 23(18), 185401 (2012).
[CrossRef] [PubMed]

T. Tayagaki, N. Usami, W. Pan, Y. Hoshi, K. Ooi, and Y. Kanemitsu, “Enhanced carrier extraction from Ge quantum dots in Si solar cells under strong photoexcitation,” Appl. Phys. Lett. 101(13), 133905 (2012).
[CrossRef]

Y. Hoshi, T. Tayagaki, T. Kiguchi, and N. Usami, “Control of geometry in Si-based photonic nanostructures formed by maskless wet etching process and its impact on optical properties,” Thin Solid Films. in press.

Huffman, M.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Jin-Phillipp, N. Y.

Z. Zhong, G. Katsaros, M. Stoffel, G. Costantini, K. Kern, O. G. Schmidt, N. Y. Jin-Phillipp, and G. Bauer, “Periodic pillar structures by Si etching of multilayer GeSi/Si islands,” Appl. Phys. Lett. 87(26), 263102 (2005).
[CrossRef]

Jørgensen, H. I.

P. Krogstrup, H. I. Jørgensen, M. Heiss, O. Demichel, J. V. Holm, M. Aagesen, J. Nygard, and A. Fontcuberta i Morral, “Single-nanowire solar cells beyond the Shockley–Queisser limit,” Nat. Photonics 7(4), 306–310 (2013).
[CrossRef]

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H. Sai, H. Fujii, K. Arafune, Y. Ohshita, M. Yamaguchi, Y. Kanamori, and H. Yugami, “Antireflective subwavelength structures on crystalline Si fabricated using directly formed anodic porous alumina masks,” Appl. Phys. Lett. 88(20), 201116 (2006).
[CrossRef]

Kanemitsu, Y.

T. Tayagaki, N. Usami, W. Pan, Y. Hoshi, K. Ooi, and Y. Kanemitsu, “Enhanced carrier extraction from Ge quantum dots in Si solar cells under strong photoexcitation,” Appl. Phys. Lett. 101(13), 133905 (2012).
[CrossRef]

T. Tayagaki, K. Ueda, S. Fukatsu, and Y. Kanemitsu, “Recombination dynamics of high-density photocarriers in type-II Ge/Si quantum dots,” J. Phys. Soc. Jpn. 81(6), 064712 (2012).
[CrossRef]

Katsaros, G.

Z. Zhong, G. Katsaros, M. Stoffel, G. Costantini, K. Kern, O. G. Schmidt, N. Y. Jin-Phillipp, and G. Bauer, “Periodic pillar structures by Si etching of multilayer GeSi/Si islands,” Appl. Phys. Lett. 87(26), 263102 (2005).
[CrossRef]

Kawakami, Y.

A. Oskooi, P. A. Favuzzi, Y. Tanaka, H. Shigeta, Y. Kawakami, and S. Noda, “Partially disordered photonic-crystal thin films for enhanced and robust photovoltaics,” Appl. Phys. Lett. 100(18), 181110 (2012).
[CrossRef]

Kelzenberg, M. D.

M. D. Kelzenberg, S. W. Boettcher, J. A. Petykiewicz, D. B. Turner-Evans, M. C. Putnam, E. L. Warren, J. M. Spurgeon, R. M. Briggs, N. S. Lewis, and H. A. Atwater, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” Nat. Mater. 9(3), 239–244 (2010).
[PubMed]

Kern, K.

Z. Zhong, G. Katsaros, M. Stoffel, G. Costantini, K. Kern, O. G. Schmidt, N. Y. Jin-Phillipp, and G. Bauer, “Periodic pillar structures by Si etching of multilayer GeSi/Si islands,” Appl. Phys. Lett. 87(26), 263102 (2005).
[CrossRef]

Kiguchi, T.

Y. Hoshi, W. Pan, T. Kiguchi, K. Ooi, T. Tayagaki, and N. Usami, “Control of dip shape in photonic nanostructures by maskless wet-etching process and its impact on optical properties,” Jpn. J. Appl. Phys. 52(8R), 080202 (2013).
[CrossRef]

N. Usami, W. Pan, T. Tayagaki, S. T. Chu, J. Li, T. Feng, Y. Hoshi, and T. Kiguchi, “Simultaneous enhanced photon capture and carrier generation in Si solar cells using Ge quantum dot photonic nanocrystals,” Nanotechnology 23(18), 185401 (2012).
[CrossRef] [PubMed]

Y. Hoshi, T. Tayagaki, T. Kiguchi, and N. Usami, “Control of geometry in Si-based photonic nanostructures formed by maskless wet etching process and its impact on optical properties,” Thin Solid Films. in press.

Kim, J. K.

J.-Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S.-Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Krogstrup, P.

P. Krogstrup, H. I. Jørgensen, M. Heiss, O. Demichel, J. V. Holm, M. Aagesen, J. Nygard, and A. Fontcuberta i Morral, “Single-nanowire solar cells beyond the Shockley–Queisser limit,” Nat. Photonics 7(4), 306–310 (2013).
[CrossRef]

Lewis, N. S.

M. D. Kelzenberg, S. W. Boettcher, J. A. Petykiewicz, D. B. Turner-Evans, M. C. Putnam, E. L. Warren, J. M. Spurgeon, R. M. Briggs, N. S. Lewis, and H. A. Atwater, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” Nat. Mater. 9(3), 239–244 (2010).
[PubMed]

Li, H. B. T.

Li, J.

N. Usami, W. Pan, T. Tayagaki, S. T. Chu, J. Li, T. Feng, Y. Hoshi, and T. Kiguchi, “Simultaneous enhanced photon capture and carrier generation in Si solar cells using Ge quantum dot photonic nanocrystals,” Nanotechnology 23(18), 185401 (2012).
[CrossRef] [PubMed]

Lin, S.-Y.

J.-Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S.-Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Liu, W.

J.-Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S.-Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Magnusson, M. H.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Meier, D. L.

H.-C. Yuan, V. E. Yost, M. R. Page, P. Stradins, D. L. Meier, and H. M. Branz, “Efficient black silicon solar cell with a density-graded nanoporous surface: optical properties, performance limitations, and design rules,” Appl. Phys. Lett. 95(12), 123501 (2009).
[CrossRef]

Mertens, R.

L. Stalmans, J. Poortmans, H. Bender, M. Caymax, K. Said, E. Vazsonyi, J. Nijs, and R. Mertens, “Porous silicon in crystalline silicon solar cells: a review and the effect on the internal quantum efficiency,” Prog. Photovolt. Res. Appl. 6(4), 233–246 (1998).
[CrossRef]

Miller, O. D.

A. Niv, M. Gharghi, C. Gladden, O. D. Miller, and X. Zhang, “Near-field electromagnetic theory for thin solar cells,” Phys. Rev. Lett. 109(13), 138701 (2012).
[CrossRef] [PubMed]

Nakajima, K.

A. Alguno, N. Usami, T. Ujihara, K. Fujiwara, G. Sazaki, K. Nakajima, and Y. Shiraki, “Enhanced quantum efficiency of solar cells with self-assembled Ge dots stacked in multilayer structure,” Appl. Phys. Lett. 83(6), 1258–1260 (2003).
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W. C. Dash and R. Newman, “Optical absorption in single-crystal germanium and silicon at 77°K and 300°K,” Phys. Rev. 99(4), 1151–1155 (1955).
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Nijs, J.

L. Stalmans, J. Poortmans, H. Bender, M. Caymax, K. Said, E. Vazsonyi, J. Nijs, and R. Mertens, “Porous silicon in crystalline silicon solar cells: a review and the effect on the internal quantum efficiency,” Prog. Photovolt. Res. Appl. 6(4), 233–246 (1998).
[CrossRef]

Niv, A.

A. Niv, M. Gharghi, C. Gladden, O. D. Miller, and X. Zhang, “Near-field electromagnetic theory for thin solar cells,” Phys. Rev. Lett. 109(13), 138701 (2012).
[CrossRef] [PubMed]

Noda, S.

A. Oskooi, P. A. Favuzzi, Y. Tanaka, H. Shigeta, Y. Kawakami, and S. Noda, “Partially disordered photonic-crystal thin films for enhanced and robust photovoltaics,” Appl. Phys. Lett. 100(18), 181110 (2012).
[CrossRef]

Nygard, J.

P. Krogstrup, H. I. Jørgensen, M. Heiss, O. Demichel, J. V. Holm, M. Aagesen, J. Nygard, and A. Fontcuberta i Morral, “Single-nanowire solar cells beyond the Shockley–Queisser limit,” Nat. Photonics 7(4), 306–310 (2013).
[CrossRef]

Ohshita, Y.

H. Sai, H. Fujii, K. Arafune, Y. Ohshita, M. Yamaguchi, Y. Kanamori, and H. Yugami, “Antireflective subwavelength structures on crystalline Si fabricated using directly formed anodic porous alumina masks,” Appl. Phys. Lett. 88(20), 201116 (2006).
[CrossRef]

Ooi, K.

Y. Hoshi, W. Pan, T. Kiguchi, K. Ooi, T. Tayagaki, and N. Usami, “Control of dip shape in photonic nanostructures by maskless wet-etching process and its impact on optical properties,” Jpn. J. Appl. Phys. 52(8R), 080202 (2013).
[CrossRef]

T. Tayagaki, N. Usami, W. Pan, Y. Hoshi, K. Ooi, and Y. Kanemitsu, “Enhanced carrier extraction from Ge quantum dots in Si solar cells under strong photoexcitation,” Appl. Phys. Lett. 101(13), 133905 (2012).
[CrossRef]

Oskooi, A.

A. Oskooi, P. A. Favuzzi, Y. Tanaka, H. Shigeta, Y. Kawakami, and S. Noda, “Partially disordered photonic-crystal thin films for enhanced and robust photovoltaics,” Appl. Phys. Lett. 100(18), 181110 (2012).
[CrossRef]

Page, M. R.

H.-C. Yuan, V. E. Yost, M. R. Page, P. Stradins, D. L. Meier, and H. M. Branz, “Efficient black silicon solar cell with a density-graded nanoporous surface: optical properties, performance limitations, and design rules,” Appl. Phys. Lett. 95(12), 123501 (2009).
[CrossRef]

Pan, W.

Y. Hoshi, W. Pan, T. Kiguchi, K. Ooi, T. Tayagaki, and N. Usami, “Control of dip shape in photonic nanostructures by maskless wet-etching process and its impact on optical properties,” Jpn. J. Appl. Phys. 52(8R), 080202 (2013).
[CrossRef]

T. Tayagaki, N. Usami, W. Pan, Y. Hoshi, K. Ooi, and Y. Kanemitsu, “Enhanced carrier extraction from Ge quantum dots in Si solar cells under strong photoexcitation,” Appl. Phys. Lett. 101(13), 133905 (2012).
[CrossRef]

N. Usami, W. Pan, T. Tayagaki, S. T. Chu, J. Li, T. Feng, Y. Hoshi, and T. Kiguchi, “Simultaneous enhanced photon capture and carrier generation in Si solar cells using Ge quantum dot photonic nanocrystals,” Nanotechnology 23(18), 185401 (2012).
[CrossRef] [PubMed]

Pattnaik, S.

J. Bhattacharya, N. Chakravarty, S. Pattnaik, W. Dennis Slafer, R. Biswas, and V. L. Dalal, “A photonic-plasmonic structure for enhancing light absorption in thin film solar cells,” Appl. Phys. Lett. 99(13), 131114 (2011).
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Petykiewicz, J. A.

M. D. Kelzenberg, S. W. Boettcher, J. A. Petykiewicz, D. B. Turner-Evans, M. C. Putnam, E. L. Warren, J. M. Spurgeon, R. M. Briggs, N. S. Lewis, and H. A. Atwater, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” Nat. Mater. 9(3), 239–244 (2010).
[PubMed]

Pillai, S.

M. A. Green and S. Pillai, “Harnessing plasmonics for solar cells,” Nat. Photonics 6(3), 130–132 (2012).
[CrossRef]

Polman, A.

Poortmans, J.

L. Stalmans, J. Poortmans, H. Bender, M. Caymax, K. Said, E. Vazsonyi, J. Nijs, and R. Mertens, “Porous silicon in crystalline silicon solar cells: a review and the effect on the internal quantum efficiency,” Prog. Photovolt. Res. Appl. 6(4), 233–246 (1998).
[CrossRef]

Prasciolu, M.

Pratesi, F.

Putnam, M. C.

M. D. Kelzenberg, S. W. Boettcher, J. A. Petykiewicz, D. B. Turner-Evans, M. C. Putnam, E. L. Warren, J. M. Spurgeon, R. M. Briggs, N. S. Lewis, and H. A. Atwater, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” Nat. Mater. 9(3), 239–244 (2010).
[PubMed]

Raman, A.

Z. Yu, A. Raman, and S. Fan, “Fundamental limit of nanophotonic light trapping in solar cells,” Proc. Natl. Acad. Sci. U.S.A. 107(41), 17491–17496 (2010).
[CrossRef] [PubMed]

Riboli, F.

F. Pratesi, M. Burresi, F. Riboli, K. Vynck, and D. S. Wiersma, “Disordered photonic structures for light harvesting in solar cells,” Opt. Express 21(S3Suppl 3), A460–A468 (2013).
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K. Vynck, M. Burresi, F. Riboli, and D. S. Wiersma, “Photon management in two-dimensional disordered media,” Nat. Mater. 11(12), 1017–1022 (2012).
[PubMed]

Sai, H.

H. Sai, H. Fujii, K. Arafune, Y. Ohshita, M. Yamaguchi, Y. Kanamori, and H. Yugami, “Antireflective subwavelength structures on crystalline Si fabricated using directly formed anodic porous alumina masks,” Appl. Phys. Lett. 88(20), 201116 (2006).
[CrossRef]

Said, K.

L. Stalmans, J. Poortmans, H. Bender, M. Caymax, K. Said, E. Vazsonyi, J. Nijs, and R. Mertens, “Porous silicon in crystalline silicon solar cells: a review and the effect on the internal quantum efficiency,” Prog. Photovolt. Res. Appl. 6(4), 233–246 (1998).
[CrossRef]

Samuelson, L.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Sazaki, G.

A. Alguno, N. Usami, T. Ujihara, K. Fujiwara, G. Sazaki, K. Nakajima, and Y. Shiraki, “Enhanced quantum efficiency of solar cells with self-assembled Ge dots stacked in multilayer structure,” Appl. Phys. Lett. 83(6), 1258–1260 (2003).
[CrossRef]

Schmidt, O. G.

Z. Zhong, G. Katsaros, M. Stoffel, G. Costantini, K. Kern, O. G. Schmidt, N. Y. Jin-Phillipp, and G. Bauer, “Periodic pillar structures by Si etching of multilayer GeSi/Si islands,” Appl. Phys. Lett. 87(26), 263102 (2005).
[CrossRef]

Schropp, R. E. I.

Schubert, E. F.

J.-Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S.-Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Schubert, M. F.

J.-Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S.-Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Shigeta, H.

A. Oskooi, P. A. Favuzzi, Y. Tanaka, H. Shigeta, Y. Kawakami, and S. Noda, “Partially disordered photonic-crystal thin films for enhanced and robust photovoltaics,” Appl. Phys. Lett. 100(18), 181110 (2012).
[CrossRef]

Shiraki, Y.

A. Alguno, N. Usami, T. Ujihara, K. Fujiwara, G. Sazaki, K. Nakajima, and Y. Shiraki, “Enhanced quantum efficiency of solar cells with self-assembled Ge dots stacked in multilayer structure,” Appl. Phys. Lett. 83(6), 1258–1260 (2003).
[CrossRef]

H. Sunamura, N. Usami, Y. Shiraki, and S. Fukatsu, “Island formation during growth of Ge on Si(100): a study using photoluminescence spectroscopy,” Appl. Phys. Lett. 66(22), 3024–3026 (1995).
[CrossRef]

Siefer, G.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Smart, J. A.

J.-Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S.-Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Spurgeon, J. M.

M. D. Kelzenberg, S. W. Boettcher, J. A. Petykiewicz, D. B. Turner-Evans, M. C. Putnam, E. L. Warren, J. M. Spurgeon, R. M. Briggs, N. S. Lewis, and H. A. Atwater, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” Nat. Mater. 9(3), 239–244 (2010).
[PubMed]

Stalmans, L.

L. Stalmans, J. Poortmans, H. Bender, M. Caymax, K. Said, E. Vazsonyi, J. Nijs, and R. Mertens, “Porous silicon in crystalline silicon solar cells: a review and the effect on the internal quantum efficiency,” Prog. Photovolt. Res. Appl. 6(4), 233–246 (1998).
[CrossRef]

Stoffel, M.

Z. Zhong, G. Katsaros, M. Stoffel, G. Costantini, K. Kern, O. G. Schmidt, N. Y. Jin-Phillipp, and G. Bauer, “Periodic pillar structures by Si etching of multilayer GeSi/Si islands,” Appl. Phys. Lett. 87(26), 263102 (2005).
[CrossRef]

Stradins, P.

H.-C. Yuan, V. E. Yost, M. R. Page, P. Stradins, D. L. Meier, and H. M. Branz, “Efficient black silicon solar cell with a density-graded nanoporous surface: optical properties, performance limitations, and design rules,” Appl. Phys. Lett. 95(12), 123501 (2009).
[CrossRef]

Sunamura, H.

H. Sunamura, N. Usami, Y. Shiraki, and S. Fukatsu, “Island formation during growth of Ge on Si(100): a study using photoluminescence spectroscopy,” Appl. Phys. Lett. 66(22), 3024–3026 (1995).
[CrossRef]

Tanaka, Y.

A. Oskooi, P. A. Favuzzi, Y. Tanaka, H. Shigeta, Y. Kawakami, and S. Noda, “Partially disordered photonic-crystal thin films for enhanced and robust photovoltaics,” Appl. Phys. Lett. 100(18), 181110 (2012).
[CrossRef]

Tayagaki, T.

T. Tayagaki, Y. Hoshi, and N. Usami, “Investigation of the open-circuit voltage in solar cells doped with quantum dots,” Sci Rep 3, 2703 (2013).
[CrossRef] [PubMed]

Y. Hoshi, W. Pan, T. Kiguchi, K. Ooi, T. Tayagaki, and N. Usami, “Control of dip shape in photonic nanostructures by maskless wet-etching process and its impact on optical properties,” Jpn. J. Appl. Phys. 52(8R), 080202 (2013).
[CrossRef]

T. Tayagaki, N. Usami, W. Pan, Y. Hoshi, K. Ooi, and Y. Kanemitsu, “Enhanced carrier extraction from Ge quantum dots in Si solar cells under strong photoexcitation,” Appl. Phys. Lett. 101(13), 133905 (2012).
[CrossRef]

N. Usami, W. Pan, T. Tayagaki, S. T. Chu, J. Li, T. Feng, Y. Hoshi, and T. Kiguchi, “Simultaneous enhanced photon capture and carrier generation in Si solar cells using Ge quantum dot photonic nanocrystals,” Nanotechnology 23(18), 185401 (2012).
[CrossRef] [PubMed]

T. Tayagaki, K. Ueda, S. Fukatsu, and Y. Kanemitsu, “Recombination dynamics of high-density photocarriers in type-II Ge/Si quantum dots,” J. Phys. Soc. Jpn. 81(6), 064712 (2012).
[CrossRef]

Y. Hoshi, T. Tayagaki, T. Kiguchi, and N. Usami, “Control of geometry in Si-based photonic nanostructures formed by maskless wet etching process and its impact on optical properties,” Thin Solid Films. in press.

Tormen, M.

Turner-Evans, D. B.

M. D. Kelzenberg, S. W. Boettcher, J. A. Petykiewicz, D. B. Turner-Evans, M. C. Putnam, E. L. Warren, J. M. Spurgeon, R. M. Briggs, N. S. Lewis, and H. A. Atwater, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” Nat. Mater. 9(3), 239–244 (2010).
[PubMed]

Ueda, K.

T. Tayagaki, K. Ueda, S. Fukatsu, and Y. Kanemitsu, “Recombination dynamics of high-density photocarriers in type-II Ge/Si quantum dots,” J. Phys. Soc. Jpn. 81(6), 064712 (2012).
[CrossRef]

Ujihara, T.

A. Alguno, N. Usami, T. Ujihara, K. Fujiwara, G. Sazaki, K. Nakajima, and Y. Shiraki, “Enhanced quantum efficiency of solar cells with self-assembled Ge dots stacked in multilayer structure,” Appl. Phys. Lett. 83(6), 1258–1260 (2003).
[CrossRef]

Usami, N.

Y. Hoshi, W. Pan, T. Kiguchi, K. Ooi, T. Tayagaki, and N. Usami, “Control of dip shape in photonic nanostructures by maskless wet-etching process and its impact on optical properties,” Jpn. J. Appl. Phys. 52(8R), 080202 (2013).
[CrossRef]

T. Tayagaki, Y. Hoshi, and N. Usami, “Investigation of the open-circuit voltage in solar cells doped with quantum dots,” Sci Rep 3, 2703 (2013).
[CrossRef] [PubMed]

T. Tayagaki, N. Usami, W. Pan, Y. Hoshi, K. Ooi, and Y. Kanemitsu, “Enhanced carrier extraction from Ge quantum dots in Si solar cells under strong photoexcitation,” Appl. Phys. Lett. 101(13), 133905 (2012).
[CrossRef]

N. Usami, W. Pan, T. Tayagaki, S. T. Chu, J. Li, T. Feng, Y. Hoshi, and T. Kiguchi, “Simultaneous enhanced photon capture and carrier generation in Si solar cells using Ge quantum dot photonic nanocrystals,” Nanotechnology 23(18), 185401 (2012).
[CrossRef] [PubMed]

A. Alguno, N. Usami, T. Ujihara, K. Fujiwara, G. Sazaki, K. Nakajima, and Y. Shiraki, “Enhanced quantum efficiency of solar cells with self-assembled Ge dots stacked in multilayer structure,” Appl. Phys. Lett. 83(6), 1258–1260 (2003).
[CrossRef]

H. Sunamura, N. Usami, Y. Shiraki, and S. Fukatsu, “Island formation during growth of Ge on Si(100): a study using photoluminescence spectroscopy,” Appl. Phys. Lett. 66(22), 3024–3026 (1995).
[CrossRef]

Y. Hoshi, T. Tayagaki, T. Kiguchi, and N. Usami, “Control of geometry in Si-based photonic nanostructures formed by maskless wet etching process and its impact on optical properties,” Thin Solid Films. in press.

van de Lagemaat, J.

E. T. Yu and J. van de Lagemaat, “Photon management for photovoltaics,” MRS Bull. 36(06), 424–428 (2011).
[CrossRef]

Vazsonyi, E.

L. Stalmans, J. Poortmans, H. Bender, M. Caymax, K. Said, E. Vazsonyi, J. Nijs, and R. Mertens, “Porous silicon in crystalline silicon solar cells: a review and the effect on the internal quantum efficiency,” Prog. Photovolt. Res. Appl. 6(4), 233–246 (1998).
[CrossRef]

Verhagen, E.

Verschuuren, M. A.

Vynck, K.

Wallentin, J.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Walters, R. J.

Wang, A.

J. Zhao, A. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, “24% efficient perl silicon solar cell: recent improvements in high efficiency silicon cell research,” Sol. Energy Mater. Sol. Cells 41–42, 87–99 (1996).
[CrossRef]

Warren, E. L.

M. D. Kelzenberg, S. W. Boettcher, J. A. Petykiewicz, D. B. Turner-Evans, M. C. Putnam, E. L. Warren, J. M. Spurgeon, R. M. Briggs, N. S. Lewis, and H. A. Atwater, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” Nat. Mater. 9(3), 239–244 (2010).
[PubMed]

Wenham, S. R.

J. Zhao, A. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, “24% efficient perl silicon solar cell: recent improvements in high efficiency silicon cell research,” Sol. Energy Mater. Sol. Cells 41–42, 87–99 (1996).
[CrossRef]

Wiersma, D. S.

Witzigmann, B.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Xi, J.-Q.

J.-Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S.-Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Xu, H. Q.

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Yablonovitch, E.

Yamaguchi, M.

H. Sai, H. Fujii, K. Arafune, Y. Ohshita, M. Yamaguchi, Y. Kanamori, and H. Yugami, “Antireflective subwavelength structures on crystalline Si fabricated using directly formed anodic porous alumina masks,” Appl. Phys. Lett. 88(20), 201116 (2006).
[CrossRef]

Yost, V. E.

H.-C. Yuan, V. E. Yost, M. R. Page, P. Stradins, D. L. Meier, and H. M. Branz, “Efficient black silicon solar cell with a density-graded nanoporous surface: optical properties, performance limitations, and design rules,” Appl. Phys. Lett. 95(12), 123501 (2009).
[CrossRef]

Yu, E. T.

E. T. Yu and J. van de Lagemaat, “Photon management for photovoltaics,” MRS Bull. 36(06), 424–428 (2011).
[CrossRef]

Yu, Z.

Z. Yu, A. Raman, and S. Fan, “Fundamental limit of nanophotonic light trapping in solar cells,” Proc. Natl. Acad. Sci. U.S.A. 107(41), 17491–17496 (2010).
[CrossRef] [PubMed]

Yuan, H.-C.

H.-C. Yuan, V. E. Yost, M. R. Page, P. Stradins, D. L. Meier, and H. M. Branz, “Efficient black silicon solar cell with a density-graded nanoporous surface: optical properties, performance limitations, and design rules,” Appl. Phys. Lett. 95(12), 123501 (2009).
[CrossRef]

Yugami, H.

H. Sai, H. Fujii, K. Arafune, Y. Ohshita, M. Yamaguchi, Y. Kanamori, and H. Yugami, “Antireflective subwavelength structures on crystalline Si fabricated using directly formed anodic porous alumina masks,” Appl. Phys. Lett. 88(20), 201116 (2006).
[CrossRef]

Zhang, X.

A. Niv, M. Gharghi, C. Gladden, O. D. Miller, and X. Zhang, “Near-field electromagnetic theory for thin solar cells,” Phys. Rev. Lett. 109(13), 138701 (2012).
[CrossRef] [PubMed]

Zhao, J.

J. Zhao, A. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, “24% efficient perl silicon solar cell: recent improvements in high efficiency silicon cell research,” Sol. Energy Mater. Sol. Cells 41–42, 87–99 (1996).
[CrossRef]

Zhong, Z.

Z. Zhong, G. Katsaros, M. Stoffel, G. Costantini, K. Kern, O. G. Schmidt, N. Y. Jin-Phillipp, and G. Bauer, “Periodic pillar structures by Si etching of multilayer GeSi/Si islands,” Appl. Phys. Lett. 87(26), 263102 (2005).
[CrossRef]

Appl. Phys. Lett. (8)

H. Sai, H. Fujii, K. Arafune, Y. Ohshita, M. Yamaguchi, Y. Kanamori, and H. Yugami, “Antireflective subwavelength structures on crystalline Si fabricated using directly formed anodic porous alumina masks,” Appl. Phys. Lett. 88(20), 201116 (2006).
[CrossRef]

H.-C. Yuan, V. E. Yost, M. R. Page, P. Stradins, D. L. Meier, and H. M. Branz, “Efficient black silicon solar cell with a density-graded nanoporous surface: optical properties, performance limitations, and design rules,” Appl. Phys. Lett. 95(12), 123501 (2009).
[CrossRef]

A. Oskooi, P. A. Favuzzi, Y. Tanaka, H. Shigeta, Y. Kawakami, and S. Noda, “Partially disordered photonic-crystal thin films for enhanced and robust photovoltaics,” Appl. Phys. Lett. 100(18), 181110 (2012).
[CrossRef]

J. Bhattacharya, N. Chakravarty, S. Pattnaik, W. Dennis Slafer, R. Biswas, and V. L. Dalal, “A photonic-plasmonic structure for enhancing light absorption in thin film solar cells,” Appl. Phys. Lett. 99(13), 131114 (2011).
[CrossRef]

A. Alguno, N. Usami, T. Ujihara, K. Fujiwara, G. Sazaki, K. Nakajima, and Y. Shiraki, “Enhanced quantum efficiency of solar cells with self-assembled Ge dots stacked in multilayer structure,” Appl. Phys. Lett. 83(6), 1258–1260 (2003).
[CrossRef]

T. Tayagaki, N. Usami, W. Pan, Y. Hoshi, K. Ooi, and Y. Kanemitsu, “Enhanced carrier extraction from Ge quantum dots in Si solar cells under strong photoexcitation,” Appl. Phys. Lett. 101(13), 133905 (2012).
[CrossRef]

H. Sunamura, N. Usami, Y. Shiraki, and S. Fukatsu, “Island formation during growth of Ge on Si(100): a study using photoluminescence spectroscopy,” Appl. Phys. Lett. 66(22), 3024–3026 (1995).
[CrossRef]

Z. Zhong, G. Katsaros, M. Stoffel, G. Costantini, K. Kern, O. G. Schmidt, N. Y. Jin-Phillipp, and G. Bauer, “Periodic pillar structures by Si etching of multilayer GeSi/Si islands,” Appl. Phys. Lett. 87(26), 263102 (2005).
[CrossRef]

J. Opt. Soc. Am. (1)

J. Phys. Soc. Jpn. (1)

T. Tayagaki, K. Ueda, S. Fukatsu, and Y. Kanemitsu, “Recombination dynamics of high-density photocarriers in type-II Ge/Si quantum dots,” J. Phys. Soc. Jpn. 81(6), 064712 (2012).
[CrossRef]

Jpn. J. Appl. Phys. (1)

Y. Hoshi, W. Pan, T. Kiguchi, K. Ooi, T. Tayagaki, and N. Usami, “Control of dip shape in photonic nanostructures by maskless wet-etching process and its impact on optical properties,” Jpn. J. Appl. Phys. 52(8R), 080202 (2013).
[CrossRef]

MRS Bull. (1)

E. T. Yu and J. van de Lagemaat, “Photon management for photovoltaics,” MRS Bull. 36(06), 424–428 (2011).
[CrossRef]

Nanotechnology (1)

N. Usami, W. Pan, T. Tayagaki, S. T. Chu, J. Li, T. Feng, Y. Hoshi, and T. Kiguchi, “Simultaneous enhanced photon capture and carrier generation in Si solar cells using Ge quantum dot photonic nanocrystals,” Nanotechnology 23(18), 185401 (2012).
[CrossRef] [PubMed]

Nat. Mater. (3)

K. Vynck, M. Burresi, F. Riboli, and D. S. Wiersma, “Photon management in two-dimensional disordered media,” Nat. Mater. 11(12), 1017–1022 (2012).
[PubMed]

H. A. Atwater and A. Polman, “Plasmonics for improved photovoltaic devices,” Nat. Mater. 9(3), 205–213 (2010).
[CrossRef] [PubMed]

M. D. Kelzenberg, S. W. Boettcher, J. A. Petykiewicz, D. B. Turner-Evans, M. C. Putnam, E. L. Warren, J. M. Spurgeon, R. M. Briggs, N. S. Lewis, and H. A. Atwater, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” Nat. Mater. 9(3), 239–244 (2010).
[PubMed]

Nat. Photonics (3)

P. Krogstrup, H. I. Jørgensen, M. Heiss, O. Demichel, J. V. Holm, M. Aagesen, J. Nygard, and A. Fontcuberta i Morral, “Single-nanowire solar cells beyond the Shockley–Queisser limit,” Nat. Photonics 7(4), 306–310 (2013).
[CrossRef]

M. A. Green and S. Pillai, “Harnessing plasmonics for solar cells,” Nat. Photonics 6(3), 130–132 (2012).
[CrossRef]

J.-Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S.-Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Opt. Express (3)

Phys. Rev. (1)

W. C. Dash and R. Newman, “Optical absorption in single-crystal germanium and silicon at 77°K and 300°K,” Phys. Rev. 99(4), 1151–1155 (1955).
[CrossRef]

Phys. Rev. Lett. (1)

A. Niv, M. Gharghi, C. Gladden, O. D. Miller, and X. Zhang, “Near-field electromagnetic theory for thin solar cells,” Phys. Rev. Lett. 109(13), 138701 (2012).
[CrossRef] [PubMed]

Proc. Natl. Acad. Sci. U.S.A. (1)

Z. Yu, A. Raman, and S. Fan, “Fundamental limit of nanophotonic light trapping in solar cells,” Proc. Natl. Acad. Sci. U.S.A. 107(41), 17491–17496 (2010).
[CrossRef] [PubMed]

Prog. Photovolt. Res. Appl. (1)

L. Stalmans, J. Poortmans, H. Bender, M. Caymax, K. Said, E. Vazsonyi, J. Nijs, and R. Mertens, “Porous silicon in crystalline silicon solar cells: a review and the effect on the internal quantum efficiency,” Prog. Photovolt. Res. Appl. 6(4), 233–246 (1998).
[CrossRef]

Sci Rep (1)

T. Tayagaki, Y. Hoshi, and N. Usami, “Investigation of the open-circuit voltage in solar cells doped with quantum dots,” Sci Rep 3, 2703 (2013).
[CrossRef] [PubMed]

Science (1)

J. Wallentin, N. Anttu, D. Asoli, M. Huffman, I. Åberg, M. H. Magnusson, G. Siefer, P. Fuss-Kailuweit, F. Dimroth, B. Witzigmann, H. Q. Xu, L. Samuelson, K. Deppert, and M. T. Borgström, “InP nanowire array solar cells achieving 13.8% efficiency by exceeding the ray optics limit,” Science 339(6123), 1057–1060 (2013).
[CrossRef] [PubMed]

Sol. Energy Mater. Sol. Cells (1)

J. Zhao, A. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, “24% efficient perl silicon solar cell: recent improvements in high efficiency silicon cell research,” Sol. Energy Mater. Sol. Cells 41–42, 87–99 (1996).
[CrossRef]

Other (4)

V. Ganapati, O. D. Miller, and E. Yablonovitch, “Spontaneous symmetry breaking in the optimization of subwavelength solar cell textures for light trapping,” 2012 38th IEEE Photovoltaic Specialists Conference (PVSC) 1572 (2012).
[CrossRef]

T. Kiguchi, Y. Hoshi, T. Tayagaki, and N. Usami, “Nanostructure and strain field in vertically aligned nano-islands for Si/Ge 2D photonic nanocrystals,” MRS Proceedings 1510, mrsf12–1510-dd05–02 (2013).
[CrossRef]

RSOFT Fullwave http://www.rsoftdesign.com

Y. Hoshi, T. Tayagaki, T. Kiguchi, and N. Usami, “Control of geometry in Si-based photonic nanostructures formed by maskless wet etching process and its impact on optical properties,” Thin Solid Films. in press.

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Figures (4)

Fig. 1
Fig. 1

(a) Schematic illustration of the side view of the surface photonic structures formed by selective wet etching using HF/HNO3 and KOH. (b) Atomic force microscope images of the photonic structures formed by HF/HNO3 (left) and KOH (right) etching. Images are ~1 × 1 μm in size. (c) Distribution of the width (left) and depth (right) of the dip formed by HF/HNO3 etching. (d) Distribution of the width (left) and depth (right) of the convex formed by KOH etching. Error bars show the FWHM of the distributions.

Fig. 2
Fig. 2

Transmission, reflection, and extinction spectra of photonic structures formed by (a) HF/HNO3 and (b) KOH etching. Inset: Extinction at 1100 nm for different etching times.

Fig. 3
Fig. 3

(a) PL and PLE spectra of the Ge/Si QDs without etching measured at 20 K. Inset: Schematic of the PLE measurements. Normalized PL intensity of Ge/Si QDs in the samples etched for different etching times with (b) HF/HNO3 and (c) KOH. Excitation wavelength dependence of the normalized PL intensity of Ge/Si QDs in the sample etched with (d) HNO3 and (e) KOH. Curves show the results for different optical thickness d = 20 (solid), 40 (dotted), and 60 nm (broken), calculated using Eq. (1).

Fig. 4
Fig. 4

(a) Schematic illustration of the photonic nanostructure used in the simulation. (b) Dip depth dependence of the electric-field density at a 1000 nm wavelength (TE and TM polarization). (c) Typical electric-field distribution for the photonic structures with a 200 nm depth. The calculation was performed for the sample without PEC reflector at the rear surface.

Equations (1)

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M= I I 0 = 1exp(αxd) 1exp(αd) ,

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