Valence-band offsets of InGaZnO4, LaAlO3, and SrTiO3 heterostructures explained by interface-induced gap states

Abstract

The intrinsic interface-induced gap states (IFIGS) which derive from the virtual gap states of the complex band structure are the fundamental mechanism that determines the band-structure lineup at semiconductor interfaces. The valence-band offsets of heterostructures are composed of a zero-charge-transfer term and an electrostatic-dipole contribution which are given by the difference of the p-type branch-point energies of the IFIGS and of the electronegativities, respectively, of the two semiconductors involved. The valence-band offsets of InGaZnO4, LaAlO3, and SrTiO3 heterostructures are quantitatively and consistently explained by the IFIGS-and-electronegativity concept. The analysis of the experimental InGaZnO4, LaAlO3, and SrTiO3 data yields the p-type branch-point energies as 2.37 ± 0.18 eV, 2.59 ± 0.13 eV, and 2.86 ± 0.14 eV, respectively.