Electronic structure, band offset, and interface electron population of the LaInO$_3$/BaSnO$_3$ system

Abstract

Perovskite oxides and their heterostructures exhibit a wide range of functional properties. Among these materials, BaSnO$_3$/LaInO$_3$ heterostructures form high-mobility two-dimensional electron gases (2DEGs) at their interfaces. In particular, room-temperature electron mobilities exceeding 100~cm$^2$/Vs were enabled by recent advances in thin-film growth. This work presents a combined experimental and theoretical study of the electronic structure of BaSnO$_3$, LaInO$_3$, and BaSnO$_3$/LaInO$_3$ heterostructures with varying LaInO$_3$ overlayer thicknesses. Soft and hard X-ray photoelectron spectroscopy (SXPS and HAXPES) measurements are combined with densities of states (DOS) derived from hybrid density functional theory (DFT) calculations. The analysis of core, semi-core, and valence states allows to arrive at a comprehensive understanding of the chemical bonding and electronic structure in the parent oxides as well as the formed heterostructures. For the BaSnO$_3$/LaInO$_3$ heterostructure, the band offset and population of 2DEG states at the interface is directly probed using HAXPES.