Direct measurement and analysis of the conduction band density of states in diluted GaAs1-xNx alloys

We use scanning tunneling spectroscopy to show directly that the conduction band density of states (DOS) of ${\text{GaAs}}_{1\ensuremath{-}x}{\text{N}}_{x}$ with low nitrogen (N) content $x$ is enhanced about 0.5 eV above the band edge, followed by a decrease at higher energy. The structure of the measured DOS is in excellent agreement with calculations based on a Green's-function formalism taking into account different N environments. This analysis highlights the inclusion of N-N pairs and the validity of the Green's-function approach to describe the band structure of dilute nitride and related extreme semiconductor alloys.