The evolution of ${\mathrm{GaAs}}_{1-x}{\mathrm{N}}_x$ band structure at low nitrogen concentrations (up to $x=0.021)$ is studied by ballistic electron emission microscopy (BEEM) spectra of ${\mathrm{A}\mathrm{u}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}}_{1-x}{\mathrm{N}}_x$ heterostructures. Two peaks observed in the second derivative BEEM spectra are identified with the contribution from the Γ- and L-like bands of ${\mathrm{GaAs}}_{1-x}{\mathrm{N}}_x.$ 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 ${\mathrm{A}\mathrm{u}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}}_{1-x}{\mathrm{N}}_x$ Schottky barrier with the nitrogen incorporation, from $\sim 0.92\hspace{0.5em}\mathrm{eV}$ at $x=0\mathrm{}$ down to $\sim 0.55\hspace{0.5em}\mathrm{eV}$ at $x=\mathrm{0.021.}\mathrm{}$ The observed Schottky barrier reduction approximates the ${\mathrm{GaAs}}_{1-x}{\mathrm{N}}_x$ band-gap reduction.

• Received 20 December 1999

DOI:https://doi.org/10.1103/PhysRevB.61.R7861