Characterization of Heteroepitaxial GaAs Films Grown on Si Using Selective Area Nucleation

Selective area growth of GaAs on patterned Si substrates is a potentially low-cost approach to integrate III-V and Si materials for multijunction solar cells. The use of nanoscale openings in a dielectric material can minimize nucleation-related defects and allow thinner buffer layers to be used to accommodate strain and trap defects caused by lattice mismatch between Si and epitaxial III-V layers. We have developed a process to grow coalesced GaAs thin films on Si substrates using buffer layers patterned by soft nanoimprint lithography (SNIL). We use photoelectrochemistry to probe the performance of these films as photovoltaic absorbers, and discuss techniques to improve the material quality of the GaAs epilayer.