Hybrid band offset calculation for heterojunction interfaces between disparate semiconductors

Abstract

Accurate band offset calculations are challenging for heterojunction interfaces that consist of two very different host materials. For this, the key requirement is to have the correct bandgap of each material at the same time. A hybrid calculation scheme (HSE/-U scheme) is proposed to model the band offsets of such interfaces. Our HSE/-U method applies the hybrid functional for the whole interface supercell, but with an additional "reverse GGA+U" on the narrow gap semiconductor side, guaranteeing the correct bandgaps on both sides. Several supercell calculations of dielectric films including HfO2, ZrO2, Al2O3, TiO2, and GaN on an insulating phase VO2 are tested to verify it. All the studied oxides show the type-I band alignment with VO2, and the band edge line-up agrees well with the available experimental reports, supporting the reliability of the proposed hybrid calculation scheme.