28.03.2016 Toward High-Efficiency Scalable III-V Solar Devices Grown via Vapor Transport from a Solid Source

Prof. Shannon Boettcher, Department of Chemistry and Materials Science Institute, University of Oregon, Eugene, USA

Date: Monday, 04.04.2016, 16:00 h
Location: WZMW, Hans-Meerwein-Str. 6 (Lahnberge), seminar room 02D36

Abstract

GaAs and related III-V semiconductors are attractive materials for high-efficiency solar photovoltaics and water-splitting photoelectrodes. Their implementation, however, is limited in part by the high cost of metal-organic chemical vapor deposition, which employs toxic and pyrophoric gas-phase precursors. We report the study of GaAs and GaAsP grown by close-space vapor transport (CSVT), which uses solid GaAs as a source and water (or chloride) vapor as a transport agent as an alternative (potentially low-cost) technique for depositing GaAs and related III-V materials. The free carrier type and density in the films was adjusted by addition of Te or Zn powder to the source powders. The minority carrier diffusion lengths of the n- and p-GaAs epitaxial films reached 2 - 3 µm and 5 - 7 µm, respectively. Hall mobilities approach those typical for GaAs grown by metal organic chemical vapor deposition. We show proof-of-concept unpassivated pn junction with open circuit voltages of 915 mV, and discuss our path forward to improve the deposition process and device performance.