Electronic Structure of GaP 1-xNx Alloys Determined Using Pseudopotentials and Gaussian Orbitals

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Abstract
A simple model based on empirical pseudopotentials, Gaussian orbitals, and the virtual-crystal approximation is employed to study the electronic structure of GaP1-x N x alloys. First, the pseudopotential form factors and the scaling parameters of the Gaussian orbitals are determined for the zinc-blende GaN constituent, and then the pseudopotential form factors are adjusted for GaP, by fitting to experimental data and the results of more accurate calculations. The band structure of the alloys is then calculated using the parameters obtained. Large nonlinear dependences of the direct Γ–Γ and indirect Γ–X gaps on nitrogen concentration are predicted. We found that the bowing parameters of these energy gaps are large, but not large enough to yield a negative band-gap energy.