Theoretical study of the band-gap anomaly of InN

Using a band-structure method that includes the correction to the band-gap error in the local-density approximation (LDA), we find that the band gap for InN is 0.8 ± 0.1 eV , in good agreement with recent experimental data, but is much smaller than previous experimental value of ∼ 1.9 eV . The unusually small band gap for InN is explained in terms of the high electronegativity of nitrogen and, consequently, the small band-gap deformation potential of InN. The possible origin of the measured large band gaps is discussed in terms of the nonparabolicity of the bands, the Moss-Burstein shift, and the effect of oxygen. Based on the error analysis of our LDA-corrected calculations we have compiled the band-structure parameters for wurtzite AlN, GaN, and InN.