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

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

^*Corresponding author for this work

School of Physics

National University of Singapore
Materials Science and Technology Division
Institute for Functional Imaging of Materials
Oak Ridge National Laboratory
Vanderbilt University
University of California at Berkeley
Trinity College Dublin

Research output: Contribution to journal › Article › peer-review

45 Scopus citations

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 (La_0.3Sr_0.7) (Al_0.65Ta_0.35)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 cm² 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.

Original language	English
Pages (from-to)	2307-2313
Number of pages	7
Journal	Nano Letters
Volume	16
Issue number	4
DOIs	https://doi.org/10.1021/acs.nanolett.5b04814
State	Published - 13 Apr 2016

Keywords

Oxide interface
carrier mobility
lattice mismatch
polar fluctuation
two-dimensional electron gas

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10.1021/acs.nanolett.5b04814

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title = "The Effect of Polar Fluctuation and Lattice Mismatch on Carrier Mobility at Oxide Interfaces",

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 cm2 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",

author = "Zhen Huang and Kun Han and Shengwei Zeng and Mallikarjuna Motapothula and Borisevich, \{Albina Y.\} and Saurabh Ghosh and Weiming L{\"u} and Changjian Li and Wenxiong Zhou and Zhiqi Liu and Michael Coey and T. Venkatesan and Ariando",

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T1 - The Effect of Polar Fluctuation and Lattice Mismatch on Carrier Mobility at Oxide Interfaces

AU - Huang, Zhen

AU - Han, Kun

AU - Zeng, Shengwei

AU - Motapothula, Mallikarjuna

AU - Borisevich, Albina Y.

AU - Ghosh, Saurabh

AU - Lü, Weiming

AU - Li, Changjian

AU - Zhou, Wenxiong

AU - Liu, Zhiqi

AU - Coey, Michael

AU - Venkatesan, T.

AU - Ariando,

PY - 2016/4/13

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N2 - 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 cm2 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.

AB - 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 cm2 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.

KW - Oxide interface

KW - carrier mobility

KW - lattice mismatch

KW - polar fluctuation

KW - two-dimensional electron gas

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JO - Nano Letters

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ER -

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

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