Evolution of GaAs1-xNx conduction states and giant Au/GaAs1-xNx Schottky barrier reduction studied by ballistic electron emission spectroscopy

The evolution of GaAs1-xNx band structure at low nitrogen concentrations (up to x=0.021) is studied by ballistic electron emission microscopy (BEEM) spectra of Au/GaAs1-xNx heterostructures. Two peaks observed in the second derivative BEEM spectra are identified with the contribution from the Gamma- and L-like bands of GaAs1-xNx. 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/GaAs1-xNx Schottky barrier with the nitrogen incorporation, from similar to 0.92 eV at x=0 down to similar to 0.55 eV at x=0.021. The observed Schottky barrier reduction approximates the GaAs1-xNx band-gap reduction.