Band offsets between ZnGeN2, GaN, ZnO, and ZnSnN2 and their potential impact for solar cells

The band offsets between the Zn-IV-N-2 nitrides, ZnGeN2 and ZnSnN2, and two other closely lattice matched semiconductors, ZnO and GaN, are calculated using density functional theory calculations including quasiparticle corrections. The interface dependence as well as the role of strain are investigated. A staggered type-II alignment is found between ZnGeN2, GaN, and ZnO, with ZnO having the lower and ZnGeN2 having the higher valence band maximum. The potential benefits of this alignment for photovoltaic applications are pointed out.