The role of oxygen vacancies in SrTiO3 at the LaAlO3/SrTiO3 interface

TL;DR

This paper investigates how oxygen vacancies in SrTiO3 influence the electronic properties of LaAlO3/SrTiO3 interfaces, revealing that oxygen deficiency significantly affects conductivity and can be manipulated during fabrication.

Contribution

It demonstrates that the electronic behavior at the interface is primarily due to oxygen vacancies in SrTiO3 and shows how these vacancies can be controlled during growth and re-oxygenation processes.

Findings

Oxygen vacancies in SrTiO3 are key to interface conductivity.

Transport properties are highly sensitive to deposition parameters.

Re-oxygenation is partly hindered by the LaAlO3 film.

Abstract

Strontium titanate, SrTiO3, a widely used substrate material for electronic oxide thin film devices, has provided many interesting features. In a combination with a similar oxide material, LaAlO3, it has recently received great interest. It was suggested that two-dimensional electron gas is formed at the interface between SrTiO3 and LaAlO3, resulting in high electrical conductivity and mobility. In this report we demonstrate that the transport properties in those heterostructures are very sensitive to the deposition parameters during thin film growth. Using cathode- and photoluminescence studies in conjunction with measurements of electrical transport properties and microstructure we show that the electronic properties observed at a LaAlO3/SrTiO3 interface can be explained by oxygen reduced SrTiO3. In addition, we demonstrate that oxygen can be pushed in and out of the sample, but that re-oxygenation of an initially oxygen depleted LaAlO3/SrTiO3 heterostructure is partly prevented by the presence of the film.