Evolution of GaAs_1-xN_x conduction states and giant Au/GaAs_1-xN_x Schottky barrier reduction studied by ballistic electron emission spectroscopy

Abstract

The evolution of GaAs_1-xN_x band structure at low nitrogen concentrations (up to x=0.021) is studied by ballistic electron emission microscopy (BEEM) spectra of Au/GaAs_1-xN_x heterostructures. Two peaks observed in the second derivative BEEM spectra are identified with the contribution from the Γ- and L-like bands of GaAs_1-xN_x. As the nitrogen concentration increases, the energetic separation between these peaks increases, with a relative decrease of the L-like band contribution to the BEEM current. In addition, we found a strong decrease of the Au/GaAs_1-xN_x Schottky barrier with the nitrogen incorporation, from ~0.92 eV at x=0 down to ~0.55 eV at x=0.021. The observed Schottky barrier reduction approximates the GaAs_1-xN_x band-gap reduction.