Modulation doping to control the high-density electron gas at a polar/non-polar oxide interface

TL;DR

This paper demonstrates a modulation-doping method to precisely control the carrier density at a polar/non-polar oxide interface, revealing insights into charge carrier origins and enabling tunable electronic properties.

Contribution

It introduces a novel modulation-doping technique to adjust electron gas density at oxide interfaces, specifically GdTiO3/SrTiO3, with experimental validation.

Findings

Carrier density reduced by up to 20% via alloying

Seebeck coefficient increases with decreasing carrier density

Provides insights into charge carrier origins at oxide interfaces

Abstract

A modulation-doping approach to control the carrier density of the high-density electron gas at a prototype polar/non-polar oxide interface is presented. It is shown that the carrier density of the electron gas at a GdTiO3/SrTiO3 interface can be reduced by up to 20% from its maximum value (~ 3x10^14 cm^-2) by alloying the GdTiO3 layer with Sr. The Seebeck coefficient of the two-dimensional electron gas increases concurrently with the decrease in its carrier density. The experimental results provide insight into the origin of charge carriers at oxide interfaces exhibiting a polar discontinuity.