Abstract
The composition dependence of the natural band alignment at nonpolar heterojunctions is investigated via hybrid functional based density functional theory. Accurate band-gap data are provided using Heyd-Scuseria-Ernzerhof (HSE) type hybrid functionals with a composition dependent exact-exchange contribution. The unstrained band alignment between zincblende (zb) semiconductor alloys is studied within the entire ternary composition range utilizing the Branch-point technique to align the energy levels related to the bulklike direct and indirect, pseudodirect, respectively, type transitions in zb-. While the zb-GaN/ band edges consistently show a type-I alignment, the relative position of fundamental band edges changes to a type-II alignment in the Al-rich composition ranges of zb- and zb- systems. The presence of a direct-indirect band-gap transition at in zb- semiconductor alloys gives rise to a notably different composition dependence of band discontinuities in the direct and indirect energy-gap ranges. Below the critical direct-indirect Al/Ga-crossover concentration, the band offsets show a close to linear dependence on the alloy composition. In contrast, notable bowing characteristics of all band discontinuities are observed above the critical crossover composition.
- Received 24 January 2017
- Revised 15 March 2017
DOI:https://doi.org/10.1103/PhysRevB.95.155310
©2017 American Physical Society