UC Berkeley

We report the use of a simple close-spaced vapor transport technique for the growth of high-quality epitaxial GaAs films using potentially inexpensive GaAs powders as precursors. The free carrier type and density (10¹⁶ to 10¹⁹ cm^-3) of the films were adjusted by addition of Te or Zn powder to the GaAs source powder. We show using photoelectrochemical and electron beam-induced current analyses that the minority carrier diffusion lengths of the n- and p-GaAs films reached ∼3 μm and ∼8 μm, respectively. Hall mobilities approach those achieved for GaAs grown by metal-organic chemical vapor deposition, 1000-4200 cm² V^-1 s^-1 for n-GaAs and 50-240 cm V^-1 s^-1 for p-GaAs depending on doping level. We conclude that the electronic quality of GaAs grown by close-spaced vapor transport is similar to that of GaAs made using conventional techniques and is thus sufficient for high-performance photovoltaic applications.