Conductivity of LaAlO/SrTiO3 Interfaces made by Sputter Deposition

TL;DR

This study examines the electrical properties of LaAlO3/SrTiO3 interfaces created by RF sputtering, revealing non-conducting interfaces due to differences in growth conditions compared to pulsed laser deposition.

Contribution

It demonstrates that sputtered LaAlO3/SrTiO3 interfaces are non-conducting, highlighting the impact of growth method on interface electronic properties.

Findings

Interfaces are atomically sharp and smooth.

Sputtered interfaces are non-conducting.

Differences in growth method affect electronic reconstruction.

Abstract

We have investigated the properties of interfaces between LaAlO3 films grown on SrTiO3 substrates singly terminated by TiO2. We used RF sputtering in a high-pressure oxygen atmosphere. The films are smooth, with flat surfaces. Transmission Electron Microscopy shows atomically sharp and continuous interfaces while EELS measurements show some slight intermixing. The elemental ratio of La to Al measured by EDX is found to be 1.07. Importantly, we find these interfaces to be non-conducting, indicating that the sputtered interface is not electronically reconstructed in the way reported for films grown by Pulsed Laser Deposition because of the different interplay between stoichiometry, mixing and oxygen vacancies.