Potential barrier lowering and electrical transport at the LaAlO$_{3}$/SrTiO$_{3}$ heterointerface

TL;DR

This study investigates how potential barrier lowering and band bending at the LaAlO$_{3}$/SrTiO$_{3}$ interface lead to metallic conductivity, revealing the spatial extent and impact on transport properties.

Contribution

It provides new insights into the mechanisms of interfacial metallicity and the effects of film thickness on transport phenomena at the heterointerface.

Findings

Barrier lowering extends over 2.5 nm into both materials.

Thinner LaAlO$_{3}$ films show higher mobility and lower carrier concentration.

Parasitic interface scattering limits low-temperature electron mobility.

Abstract

Using a combination of vertical transport measurements across and lateral transport measurements along the LaAlO$_{3}$/SrTiO$_{3}$ heterointerface, we demonstrate that significant potential barrier lowering and band bending are the cause of interfacial metallicity. Barrier lowering and enhanced band bending extends over 2.5 nm into LaAlO$_{3}$ as well as SrTiO$_{3}$. We explain origins of high-temperature carrier saturation, lower carrier concentration, and higher mobility in the sample with the thinnest LaAlO$_{3}$ film on a SrTiO$_{3}$ substrate. Lateral transport results suggest that parasitic interface scattering centers limit the low-temperature lateral electron mobility of the metallic channel.