| Popis: |
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 Gartner 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. |
