The Effect of Polar Fluctuation and Lattice Mismatch on Carrier Mobility at Oxide Interfaces

Zhen Huang; Kun Han; Shengwei Zeng; Mallikarjuna Motapothula; Albina Y Borisevich; Saurabh Ghosh; Weiming Lü; Changjian Li; Wenxiong Zhou; Zhiqi Liu; Michael Coey; T Venkatesan; Ariando

doi:10.1021/acs.nanolett.5b04814

The Effect of Polar Fluctuation and Lattice Mismatch on Carrier Mobility at Oxide Interfaces

Nano Lett. 2016 Apr 13;16(4):2307-13. doi: 10.1021/acs.nanolett.5b04814. Epub 2016 Mar 14.

Authors

Zhen Huang^{1

2}, Kun Han^{1

2}, Shengwei Zeng^{1

2}, Mallikarjuna Motapothula^{1

2}, Albina Y Borisevich, Saurabh Ghosh³, Weiming Lü⁴, Changjian Li¹, Wenxiong Zhou^{1

2}, Zhiqi Liu⁵, Michael Coey^{1

6}, T Venkatesan^{1

2

7

8

9}, Ariando^{1

2

9}

Affiliations

¹ NUSNNI-NanoCore, National University of Singapore , 117411 Singapore.
² Department of Physics, National University of Singapore , 117542 Singapore.
³ Department of Physics and Astronomy, Vanderbilt University , Nashville, Tennessee 37235, United States.
⁴ Condensed Matter Science and Technology Institute, School of Science, Harbin Institute of Technology , Harbin 150081, People's Republic of China.
⁵ Department of Materials Science and Engineering, University of California , Berkeley, California 94720, United States.
⁶ School of Physics and CRANN, Trinity College , Dublin 2, Ireland.
⁷ Department of Electrical and Computer Engineering, National University of Singapore , 117576 Singapore.
⁸ Department of Materials Science and Engineering, National University of Singapore , Singapore 117575, Singapore.
⁹ National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS) , 28 Medical Drive, Singapore 117456, Singapore.

PMID: 26959195
DOI: 10.1021/acs.nanolett.5b04814

Abstract

Since the discovery of two-dimensional electron gas (2DEG) at the oxide interface of LaAlO3/SrTiO3 (LAO/STO), improving carrier mobility has become an important issue for device applications. In this paper, by using an alternate polar perovskite insulator (La0.3Sr0.7) (Al0.65Ta0.35)O3 (LSAT) for reducing lattice mismatch from 3.0% to 1.0%, the low-temperature carrier mobility has been increased 30 fold to 35,000 cm(2) V(-1) s(-1). Moreover, two critical thicknesses for the LSAT/STO (001) interface are found, one at 5 unit cells for appearance of the 2DEG and the other at 12 unit cells for a peak in the carrier mobility. By contrast, the conducting (110) and (111) LSAT/STO interfaces only show a single critical thickness of 8 unit cells. This can be explained in terms of polar fluctuation arising from LSAT chemical composition. In addition to lattice mismatch and crystal symmetry at the interface, polar fluctuation arising from composition has been identified as an important variable to be tailored at the oxide interfaces to optimize the 2DEG transport.

Keywords: Oxide interface; carrier mobility; lattice mismatch; polar fluctuation; two-dimensional electron gas.

Publication types

Research Support, Non-U.S. Gov't