Dresden 2020 – scientific programme
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DS: Fachverband Dünne Schichten
DS 27: Focus Session: Functional Metal Oxides for Novel Applications and Devices I (joint session HL/DS)
DS 27.1: Invited Talk
Wednesday, March 18, 2020, 15:00–15:30, POT 81
Modulation Doping in High-Mobility Alkaline-Earth Stannates — •Bharat Jalan — Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, U.S.A.
Interfaces between perovskite oxides have created tremendous excitement because of the potential for emergent phenomena and novel field-effect devices. The vast majority of these papers focus on the LaAlO3/SrTiO3 (LAO/STO) interfaces including some on Al2O3/STO and ReTiO3/STO (Re refers to the rare-earth elements) interfaces among others. Amazingly, all these heterostructures involve the use of STO as an active layer where electron transport occurs. Attempts to synthesize non-STO based modulation-doped heterostructure have been unsuccessful so far despite theoretical predictions. Nor has any appreciable level of control been gained over the electron density at the interface, which is critical to device applications.
In this talk, we will report the first demonstration of true modulation doping in a wider bandgap perovskite oxides without the use of STO. We show that the La-doped SrSnO3/BaSnO3 system precisely fulfills the theoretical criteria for electron doping in BaSnO3 using electrons from La-doped SrSnO3, and we demonstrate how rearrangement of electrons can be used to control the insulator-to-metal transition in these heterostructure. We further show the use of angle-resolved HAXPES as a non-destructive approach to not only determine the location of electrons at the interface but also to quantify the width of electron distribution in BaSnO3. The transport results are in good agreement with the results of self-consistent solution to one-dimensional Poisson and Schrödinger equations.