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, 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 cm2V-1s-1. Moreover, two critical thicknesses for the LSAT/SrTiO3 (001) interface are found: one at 5 unit cell for appearance of the 2DEG, the other at 12 unit cell 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 optimise the 2DEG transport.

17 pages, 4 figures

References in corpus (8)

• Magnetic effects at the interface between nonmagnetic oxides
• A high-mobility two-dimensional electron gas at the heteroepitaxial spinel/perovskite complex oxide interface of γ-Al2O3/SrTiO3
• Suppression of Octahedral Tilts and Associated Changes of Electronic Properties at Epitaxial Oxide Heterostructure Interfaces
• A polarity-induced defect mechanism for conductivity and magnetism at polar-nonpolar oxide interfaces
• High mobility conduction at (110) and (111) LaAlO3/SrTiO3 interfaces
• Effect of symmetry mismatch on the domain structure of rhombohedral BiFeO3 thin films
• Quantum longitudinal and Hall transport at the LaAlO3/SrTiO3 interface at low electron densities
• Band alignment of epitaxial SrTiO3 thin films with (LaAlO3)0.3-(Sr2AlTaO6)0.7 (001)

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• Nanoscale Sr${}_2$IrO${}_4$ Freestanding Thin-Films for Flexible Electronics
• Two-Dimensional Electron Gas with High Mobility Forming at BaO/SrTiO3 Interface
• Buried Moire supercells through SrTiO${}_3$ nanolayer relaxation
• Electrostatic tuning of magnetism at the conducting (111) (La${}_{0.3}$Sr${}_{0.7}$)(Al${}_{0.65}$Ta${}_{0.35}$)/SrTiO${}_3$ interface
• Low temperature magnetoresistance of (111) (La${}_{0.3}$Sr${}_{0.7}$)(Al${}_{0.65}$Ta${}_{0.35}$)/SrTiO${}_3$
• Polarity-field driven conductivity in SrTiO${}_3$/LaAlO${}_3$: a hybrid functional study
• Strong spin-orbit coupling and magnetism in (111) (La${}_{0.3}$Sr${}_{0.7}$)(Al${}_{0.65}$Ta${}_{0.35})$/SrTiO${}_3$
• Electrostatic gate-controlled quantum interference in a high-mobility two-dimensional electron gas at the (La${}_{0.3}$Sr${}_{0.7}$)(Al${}_{0.65}$Ta${}_{0.35}$)O${}_3$/SrTiO${}_3$ interface