High Mobility Two-Dimensional Electron Gas at the BaSnO${}_3$/SrNbO${}_3$ Interface

Abstract

Oxide two-dimensional electron gases (2DEGs) promise high charge carrier concentrations and low-loss electronic transport in semiconductors such as BaSnO${}_3$ (BSO). ACBN0 computations for BSO/SrNbO${}_3$ (SNO) interfaces show Nb-4$\text{d}$ electron injection into extended Sn-5$\text{s}$ electronic states. The conduction band minimum consists of Sn-5$\text{s}$ states ~1.2 eV below the Fermi level for intermediate thickness 6-unit cell BSO/6-unit cell SNO superlattices, corresponding to an electron density in BSO of ~10${}^{21}$ cm${}^{-3}$. Experimental studies of analogous SNO/BSO interfaces grown by molecular beam epitaxy confirm significant charge transfer from SNO to BSO. $\text{In situ}$ angle-resolved X-ray photoelectron spectroscopy studies show an electron density of ~4 $\times$ 10${}^{21}$ cm${}^{-3}$. The consistency of theory and experiment shows that BSO/SNO interfaces provide a novel materials platform for low loss electron transport in 2DEGs.

There are 7 Figures, 1 Table and 10 pages