Influence of composition fluctuations and strain on gap bowing inInxGa1−xN

We present parameter-free calculations of electronic properties of ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{N}$ alloys based on a generalized quasichemical approach and a pseudopotential-plane-wave method. The gap fluctuations in the alloy allow the definition of a minimum gap and an average gap with different bowing parameters. Biaxial strain drastically reduces the gap fluctuations, resulting in a reduction of the bowing. The different gaps and the strain influence investigated here provide an explanation for the discrepancies found in the experimental values of the bowing parameter.