Epitaxial thin film GaAs deposited by MOCVD on low-cost, flexible substrates for high efficiency photovoltaics

Growth of epitaxial GaAs thin film on flexible, inexpensive substrates can open up the possibility of fabricating affordable and high efficiency III-V photovoltaics which may lead to a complete transformation of the PV market. Here we report the successful hetero-epitaxial growth of GaAs thin film by metal organic chemical vapor deposition on single-crystallinelike Ge thin film on flexible metal foils. GaAs epilayers showed (00l) orientation with zinc blende structure and good optoelectronic quality with minimal thermoelastic/lattice mismatch strain. High doping density due to Ge diffusion from the substrate was observed in the GaAs film with a Hall mobility of 285 cm
²
/V-s. XPS depth profiles showed significant diffusion of Ge in GaAs thin film.