The group-III nitride semiconductors represent a very unique material system with many outstanding features such as wide tunable band gap (6.2 eV for AlN, 3.4 eV for GaN, and 0.7 eV for InN)[1] [2] , high mechanical and thermal stability, and excellent electro-optical properties.

The ground state electronic structure of wurtzite AlN, GaN, and InN has been calculated using full-relativistic all-electron full-potential linearized-augmented plane-wave method. Several DFT exchange-correlation functional[3], including the recently proposed a Modified Becke-Johnson generalised gradient approximation (MBJ-GGA)[4] have been used. In our current work, we focus on the role played by MBJ-GGA functional on the band structures and the density of states. We find that the MBJ-GGA improves the accuracy of the energy gap and the semi core d states levels. This new functional slightly outperforms both the local density approximation (LDA) and the generalized gradient approximation (GGA) overall as to energy gaps, and valence band widths. We find also that the MBJ-GGA induced modifications of the band structure are significant, but limited to the energy gaps, while leaving all other features identical to LDA and GGA calculations. Our theoretical results can be used to predict group III-nitride nanostructures.

Keywords: Density functional theory, Local density approximation, Generalized gradient approximation, MBJ, Electronic structure, Nitrides.

References

[1]  S. Nakamura, M. Senoh, S.-i. Nagahama, N. Iwasa, T. Yamada, T. Matsushita, Y. Sugimoto, and H. Kiyoku, "High-power, long-lifetime InGaN multi-quantum-well-structure laser diodes," Japanese Journal of Applied Physics, vol. 36, p. L1059, 1997.

[2] S. Nakamura, "InGaN-based violet laser diodes," Semiconductor Science and Technology, vol. 14, p. R27, 1999.

[3] Hohenberg P. and Kohn W., Phys. Rev., 136 (1964) B864; Kohn W. and Sham L. J., Phys. Rev., 140 (1965) A1133.