Electronic properties of buried hetero-interfaces of LaAlO3 on SrTiO3

TL;DR

This study investigates the electronic properties of LaAlO3/SrTiO3 heterointerfaces, revealing the roles of oxygen vacancies and the minimal impact of LaAlO3 on carrier density, through transport and spectroscopic measurements.

Contribution

It provides detailed analysis of how oxygen vacancies influence charge carriers at LaAlO3/SrTiO3 interfaces, using combined transport and spectroscopic techniques.

Findings

Maximum sheet carrier density of 10^16 cm^-2

Mobility around 10^4 cm^2 V^-1 s^-1

Oxygen vacancies significantly affect charge creation

Abstract

We have made very thin films of LaAlO3 on TiO2 terminated SrTiO3 and have measured the properties of the resulting interface in various ways. Transport measurements show a maximum sheet carrier density of 1016 cm-2 and a mobility around 104 cm2 V-1 s-1. In situ ultraviolet photoelectron spectroscopy (UPS) indicates that for these samples a finite density of states exists at the Fermi level. From the oxygen pressure dependence measured in both transport as well as the UPS, we detail, as reported previously by us, that oxygen vacancies play an important role in the creation of the charge carriers and that these vacancies are introduced by the pulsed laser deposition process used to make the heterointerfaces. Under the conditions studied the effect of LaAlO3 on the carrier density is found to be minimal.