Partial carrier freeze-out at the LaAlO3/SrTiO3 oxide interface

Authors

Simon Meaney, University of WollongongFollow
Alexey Pan, University of Wollongong, National Research Nuclear UniversityFollow
Antony Jones, University of Wollongong, CSIRO ManufacturingFollow
Sergey Fedoseev, University of WollongongFollow

RIS ID

139615

Publication Details

Meaney, S., Pan, A. V., Jones, A. & Fedoseev, S. A. (2019). Partial carrier freeze-out at the LaAlO3/SrTiO3 oxide interface. APL Materials, 7 (10), 101105-1-101105-5.

Abstract

High quality robust two-dimensional electron gas (2DEG) LaAlO3/SrTiO3 (LAO/STO) interfaces are produced using pulsed laser deposition and an acid-free substrate Ti-Termination process, resulting in single unit cell terraces. Temperature dependent resistance measurements show two hysteresis anomalies around 80 K and 160 K. By using Hall measurements, we find an Arrhenius dependence in charge carrier density describing a partial carrier freeze-out below ∼80 K. We show that these two resistance anomalies are unrelated to the temperature dependence of the charge carrier density despite the tempting coincidence of the low temperature hysteresis feature and the freeze-out process. A two-carrier model is required to accurately estimate the activation energy of the thermally activated type charge carriers, which are found to be ∼5 to 7 meV. These results support the theory that oxygen vacancy defects contribute to the metallic conductivity at the 2DEG LAO/STO interface even for annealed samples.