Hybrid functional investigations of band gaps and band alignments for AlN, GaN, InN, and InGaN

Abstract

Band gaps and band alignments for AlN, GaN, InN, and InGaN alloys are investigated using density functional theory with the with the Heyd-Scuseria-Ernzerhof {HSE06 [J. Heyd, G. E. Scuseria, and M. Ernzerhof, J. Chem. Phys. 134, 8207 (2003); 124, 219906 (2006)]} XC functional. The band gap of InGaN alloys as a function of In content is calculated and a strong bowing at low In content is found, described by bowing parameters 2.29 eV at 6.25% and 1.79 eV at 12.5%, indicating the band gap cannot be described by a single composition-independent bowing parameter. Valence-band maxima (VBM) and conduction-band minima (CBM) are aligned by combining bulk calculations with surface calculations for nonpolar surfaces. The influence of surface termination [(1100) mplane or (1120) a-plane] is thoroughly investigated. We find that for the relaxed surfaces of the binary nitrides the difference in electron affinities between m-and a-plane is less than 0.1 eV. The absolute electron affinities are found to strongly depend on the choice of XC functional. However, we find that relative alignments are less sensitive to the choice of XC functional. In particular, we find that relative alignments may be calculated based on Perdew-Becke-Ernzerhof [J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Lett. 134, 3865 (1996)] surface calculations with the HSE06 lattice parameters. For InGaN we find that the VBM is a linear function of In content and that the majority of the band-gap bowing is located in the CBM. Based on the calculated electron affinities we predict that InGaN will be suited for water splitting up to 50% In content.

Impact of cation-based localized electronic states on the conduction and valence band structure of Al1−xInxN alloys

“…(1), 5 but with GaInN showing some deviations from this simple description. 6,7 A similar behavior might therefore also be expected for Al 1Àx In x N. We note however that AlInN has been reported to have a very large and composition-dependent bowing parameter, with values of b ranging from $2.5 eV (high In content) 8 to 10.3 eV (low In content). 9 A large bowing parameter has to date generally been associated with the presence of isoelectronic states in a semiconductor alloy, such as ZnTe 1Àx Se x .…”

First-principles study of band alignments in the p-type hosts BaM2X2(M= Cu, Ag;X= S, Se)

“…[14,15] A supercell was constructed and stacked along a non-polar direction (y as shown in Fig. 2) using the optimized atomic structure obtained by the PBE functional.…”

Modeling with Hybrid Density Functional Theory the Electronic Band Alignment at the Zinc Oxide–Anatase Interface

“…Such band alignment characteristics have been subject of many studies; these can be experimental, being based e.g. on spectroscopies (like XPS/UPS 1,2,3 or the STM-based ones 4,5 ) or on the measurement of I-V curves 6,7 , or theoretical, where different more or less sophisticated approaches can be followed in the calculations 8,9,10,11 .…”