Effect of non-parabolicity on the density of states for high-field mobility calculations in dilute nitrides

Using the 2-level band anticrossing (BAC) model or its generalisation to n-bands, the essential features of the non-parabolicity of the band structure in dilute nitride materials can be captured using a k.p - like formulation. However, the derived densities of states in both 3D and 2D are then badly behaved near the nitrogen impurity levels with unrealistic consequences. Densities of states in the general n-band case are derived using a Green's function approach, which are well-behaved and conserve the number of states in the crystal.