Band offsets in GaAs/amorphous Ge and GaP/amorphous Ge heterojunctions measured by internal photoemission

Abstract
Internal photoemission has been used to determine the valence- and conduction-band discontinuities (ΔEv and ΔEc) in GaAs/amorphous Ge and GaP/amorphous Ge heterojunctions. The method is straightforward, accurate, and assumes a minimum of unknown parameters. We have found ΔEv =(0.43±0.05) eV and ΔEc =(0.34±0.05) eV for GaAs/a-Ge and ΔEv =(0.88±0.05) eV and ΔEc =(0.68±0.05) eV for GaP/a-Ge.