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

摘要

Strontium titanate, SrTiO3, a widely used substrate material for electronicoxide thin film devices, has provided many interesting features. In acombination with a similar oxide material, LaAlO3, it has recently receivedgreat interest. It was suggested that two-dimensional electron gas is formed atthe interface between SrTiO3 and LaAlO3, resulting in high electricalconductivity and mobility. In this report we demonstrate that the transportproperties in those heterostructures are very sensitive to the depositionparameters during thin film growth. Using cathode- and photoluminescencestudies in conjunction with measurements of electrical transport properties andmicrostructure we show that the electronic properties observed at aLaAlO3/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 thatre-oxygenation of an initially oxygen depleted LaAlO3/SrTiO3 heterostructure ispartly prevented by the presence of the film.