Separating Electrons and Donors in BaSnO3 via Band Engineering

TL;DR

This paper demonstrates modulation doping in BaSnO3 using La-doped SrSnO3, revealing band offsets and electron transfer mechanisms that advance oxide electronics beyond SrTiO3-based systems.

Contribution

It introduces a novel modulation-doping approach in BaSnO3 with detailed spectroscopic and transport analysis, expanding oxide heterostructure functionalities.

Findings

Valence band offset of 0.71 eV between LSSO and BSO

Confirmation of two-channel conduction due to electron transfer

Electrons distributed over 2-3 unit cells in BSO

Abstract

Through a combination of thin film growth, hard X-ray photoelectron spectroscopy (HAXPES), scanning transmission electron microscopy/electron energy loss spectroscopy (STEM/EELS), magneto-transport measurements, and transport modeling, we report on the demonstration of modulation-doping of BaSnO3 (BSO) using a wider bandgap La-doped SrSnO3 (LSSO) layer. Hard X-ray photoelectron spectroscopy (HAXPES) revealed a valence band offset of 0.71 +/- 0.02 eV between LSSO and BSO resulting in a favorable conduction band offset for remote doping of BSO using LSSO. Nonlinear Hall effect of LSSO/BSO heterostructure confirmed two-channel conduction owing to electron transfer from LSSO to BSO and remained in good agreement with the results of self-consistent solution to one-dimensional Poisson and Schr\"odinger equations. Angle-dependent HAXPES measurements revealed a spatial distribution of electrons over 2-3 unit cells in BSO. These results bring perovskite oxides a step closer to room-temperature oxide electronics by establishing modulation-doping approaches in non-SrTiO3-based oxide heterostructure.