Band structure parameters of the nitrides: The origin of the small band gap of InN

TL;DR

This paper uses an improved band-structure method to accurately predict the small band gap of InN, explaining its origin and providing recommended parameters for related nitrides.

Contribution

It introduces a corrected LDA approach to accurately determine the band gap of InN and explains its small value compared to previous experimental estimates.

Findings

Predicted InN band gap of 0.8 +/- 0.1 eV, smaller than prior estimates.

Attributed small band gap to nitrogen electronegativity and band deformation potential.

Provided recommended band structure parameters for AlN, GaN, and InN.

Abstract

Using a band-structure method that includes the correction to the band gap error in the local density approximation (LDA), we study the chemical trends of the band gap variation in III-V semiconductors and predict that the band gap for InN is 0.8 +/- 0.1 eV, which is much smaller than previous experimental value of approx. 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 non-parabolicity of the bands and the Moss-Burstein shift. Based on the error analysis of our LDA calculation and available experimental data we have compiled the recommended band structure parameters for wurtzite AlN, GaN and InN.