Reduction of bulk and surface recombination in GaAs for improved solar cell performance

A technique for suppressing recombination centers and increasing minority-carrier diffusion lengths in bulk n-type GaAs is described. It is shown that such pretreatment of the material leads to substantially improved long-wavelength photocurrent collection in Zn-diffused solar cells fabricated directly in the bulk substrates. Passivation of the front surface of the cells with ammonium sulfide improves their short-wavelength photoresponse. These results suggest the possibility of realizing high-efficiency GaAs solar cells fabricated without the use of costly epitaxial technology.<>