Tuning the Two-Dimensional Electron Gas at Oxide Interfaces with Ti-O Configurations: Evidence from X-ray Photoelectron Spectroscopy

Yu Zhang; Yulin Gan; Wei Niu; Kion Norrman; Xi Yan; Dennis Valbjørn Christensen; Merlin von Soosten; Hongrui Zhang; Baogen Shen; Nini Pryds; Jirong Sun; Yunzhong Chen

doi:10.1021/acsami.7b16510

Tuning the Two-Dimensional Electron Gas at Oxide Interfaces with Ti-O Configurations: Evidence from X-ray Photoelectron Spectroscopy

ACS Appl Mater Interfaces. 2018 Jan 10;10(1):1434-1439. doi: 10.1021/acsami.7b16510. Epub 2017 Dec 22.

Authors

Yu Zhang^{1

2

3}, Yulin Gan³, Wei Niu³, Kion Norrman³, Xi Yan^{1

2}, Dennis Valbjørn Christensen³, Merlin von Soosten³, Hongrui Zhang^{1

2}, Baogen Shen^{1

2}, Nini Pryds³, Jirong Sun^{1

2}, Yunzhong Chen³

Affiliations

¹ Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences , Beijing 100190, Peoples' Republic of China.
² School of Physical Sciences, University of Chinese Academy of Sciences , Beijing 100049, People's Republic of China.
³ Department of Energy Conversion and Storage, Technical University of Denmark , Risø Campus, 4000 Roskilde, Denmark.

PMID: 29226677
DOI: 10.1021/acsami.7b16510

Abstract

A chemical redox reaction can lead to a two-dimensional electron gas at the interface between a TiO₂-terminated SrTiO₃ (STO) substrate and an amorphous LaAlO₃ capping layer. When replacing the STO substrate with rutile and anatase TiO₂ substrates, considerable differences in the interfacial conduction are observed. On the basis of X-ray photoelectron spectroscopy (XPS) and transport measurements, we conclude that the interfacial conduction comes from redox reactions, and that the differences among the materials systems result mainly from variations in the activation energies for the diffusion of oxygen vacancies at substrate surfaces.

Keywords: SrTiO3; TiO2; oxygen vacancies; redox reaction; two-dimensional electron gas.