Towards low-cost high-efficiency GaAs photovoltaics and photoelectrodes grown via vapor transport from a solid source

GaAs is an attractive material for thin-film photovoltaic applications, but is not widely used for terrestrial power generation due to the high cost of metal-organic chemical vapor deposition (MOCVD) techniques typically used for growth. Close space vapor transport is an alternative that allows for rapid growth rates of III-V materials, and does not rely on the toxic and pyrophoric precursors used in MOCVD. We characterize CSVT films of GaAs using photoelectrochemical current-voltage and quantum efficiency measurements. Hole diffusion lengths which exceed 1.5 μm are extracted from internal quantum efficiency measurements using the Gärtner model. Device physics simulations suggest that solar cells based on these films could reach efficiencies exceeding 24%. To reach this goal, a more complete understanding of the electrical properties and characterization of defects will be necessary, including measurements on complete solid-state devices. Doping of films is achieved by using source material containing the desired impurity (e.g., Te or Zn). We discuss strategies for growing III-V materials on inexpensive substrates that are not lattice-matched to GaAs.

[1]  Sumio Matsuda,et al.  GaAs solar cells grown on Si substrates for space use , 2001 .

[2]  R. Leonelli,et al.  Doping and Residual Impurities in Gaas-layers Grown By Close-spaced Vapor Transport , 1993 .

[3]  F. Nicoll.  The Use of Close Spacing in Chemical‐Transport Systems for Growing Epitaxial Layers of Semiconductors , 1963 .

[4]  D. A. Clugston,et al.  PC1D version 5: 32-bit solar cell modeling on personal computers , 1997, Conference Record of the Twenty Sixth IEEE Photovoltaic Specialists Conference - 1997.

[5]  G. Perrier,et al.  Growth of semiconductors by the close-spaced vapor transport technique: A review , 1988 .

[6]  S. Ghandhi,et al.  Improved photoluminescence of GaAs in ZnSe/GaAs heterojunctions grown by organometallic epitaxy , 1988 .

[7]  Luke J. Mawst,et al.  Nanofabrication of III–V semiconductors employing diblock copolymer lithography , 2010 .

[8]  M. Mauk,et al.  GaAs-on-silicon conformal vapor-phase epitaxy using reversible transport and selective etching reactions with water vapour , 2001 .

[9]  S. Boettcher,et al.  Efficient n-GaAs photoelectrodes grown by close-spaced vapor transport from a solid source. , 2012, ACS applied materials & interfaces.

[10]  J. Sites,et al.  Cadmium Telluride Solar Cells , 2011 .

[11]  E. Bakkers,et al.  Epitaxial Growth of III-V Nanowires on Group IV Substrates , 2008 .

[12]  Martin A. Green,et al.  Solar cell efficiency tables (version 41) , 2013 .

[13]  A. Hurd,et al.  Energy-critical elements for sustainable development , 2012 .

[14]  S. Boettcher,et al.  Towards high-efficiency GaAs thin-film solar cells grown via close space vapor transport from a solid source , 2012, 2012 38th IEEE Photovoltaic Specialists Conference.

[15]  H. Atwater,et al.  GaAs Passivation with Trioctylphosphine Sulfide for Enhanced Solar Cell Efficiency and Durability , 2012 .