Window layer properties of GaP films grown on Si by liquid phase epitaxy

Good surface passivation is necessary to achieve high efficiencies in silicon solar cells. One method is to epitaxially grow wide bandgap semiconductor materials on the silicon to act as a window layer that provides surface passivation and a minority carrier reflector. GaP and Si have a low lattice mismatch of 0.37% which is favorable for epitaxial growth while the growth of GaP on Si has the effect of doping the underlying Si n-type via phosphorus diffusion. Thin films of GaP have been grown on single crystalline ptype Si by liquid phase epitaxy (LPE) to investigate the silicon passivation and doping properties of GaP. The resulting GaP films were characterized by x-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS). Lifetime measurements were made to investigate the surface passivation properties.