Scavenging of oxygen from SrTiO3 during oxide thin film deposition and the formation of interfacial 2DEGs

Abstract

SrTiO3 is a widely used substrate for the growth of other functional oxide thin films. The reactivity of the substrate with respect to the film during deposition, particularly with regard to redox reactions, has typically been glossed over. We demonstrate by depositing a variety of metals (Ti, Al, Nb, Pt, Eu, and Sr) and measuring the in situ core level spectra of both the metal and SrTiO3 that, depending on the oxide formation energy and work function of the metal, three distinct types of behavior occur in thin metal films on SrTiO3 (100). In many cases, there will be an interfacial layer of oxygen-deficient SrTiO3 formed at the interface with the overlying film. We discuss how this may affect the interpretation of the well-known two-dimensional electron gas present at the interface between SrTiO3 and various oxides.