Wide bandgap passivation layers on silicon

The research problem addressed is the deposition of ZnS, ZnS0.9Se0.1, and GaP, which are candidate lattice-matched wide-bandgap materials intended to replace SiO2 passivation on silicon solar cells. Ideally, these films would reflect minority carriers but not impede majority carrier transport to the surface and would passivate beneath contacts. The thin films were deposited by MOCVD, resistance evaporation or sputtering. Epitaxial GaP and ZnS films were found to cause increases of internal quantum efficiency at short wavelengths. Reductions in J0 comparable to that generated by SiO2 and increases in Voc were also observed. Film growth morphology was found to be a function of substrate temperature, orientation and the success of in situ removal of the native oxide.