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

electron Microscopy and Microanalysis

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

37 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 - Apr 13 2016

Funding

We thank H. Hilgenkamp, S. Saha, Q. He, and C. G. Li for the discussion. This work is supported by the National University of Singapore (NUS) Academic Research Fund (AcRF Tier 1 Grant No. R-144-000-346-112 and R-144-000-364-112) and the Singapore National Research Foundation (NRF) under the Competitive Research Programs (CRP Award No. NRF-CRP 8-2011-06 and CRP Award No. NRF-CRP10-2012-02).

Funders	Funder number
National University of Singapore	R-144-000-364-112, R-144-000-346-112
National Research Foundation Singapore	NRF-CRP 8-2011-06, NRF-CRP10-2012-02

Keywords

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

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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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.",

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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.

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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.

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

Abstract

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Keywords

UN SDGs

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