In this Letter, we report on the evolution of electronic properties governed by epitaxial misfit strain in cubic In2O3 epilayers grown on sapphire. At elevated growth temperature, the competition between the film/substrate lattice mismatch and the thermal expansion mismatch alters the macroscopic biaxial strain from compressive to tensile. Simultaneously, the electron concentration is tuned from degeneration to non-degeneration density below the Mott criterion. The observed surface electron accumulation and metal-insulator transition result from the oxygen deficiency formed at low growth temperature, while high-temperature epitaxy is favorable to achieve remarkably enhanced mobility. The effective strain-property coupling suggests that the improved oxygen stoichiometry and the Fermi level movement controlled by the biaxial strains are responsible for the Mott transition. The strain-mediated reduction of the electron effective mass contributes to the enhanced intrinsic mobility in tensile-strained In2O3 epilayers. These results highlight that strain engineering is an effective stimulus to manipulate the transport properties of oxide semiconductors with improved performance and unexpected functionalities.

中文翻译：

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错配外延应变操纵立方 In2O3 异质外延层中的传输特性

在这封信中，我们报告了由在蓝宝石上生长的立方 In2O3 外延层中的外延失配应变控制的电子特性的演变。在升高的生长温度下，薄膜/衬底晶格失配和热膨胀失配之间的竞争将宏观双轴应变从压缩变为拉伸。同时，在莫特准则下，电子浓度从简并到非简并密度。观察到的表面电子积累和金属-绝缘体转变是由于在低生长温度下形成的氧缺陷造成的，而高温外延有利于实现显着增强的迁移率。有效的应变-性质耦合表明，由双轴应变控制的改进的氧化学计量和费米能级运动是莫特转变的原因。电子有效质量的应变介导减少有助于增强拉伸应变 In2O3 外延层中的固有迁移率。这些结果突出表明，应变工程是一种有效的刺激，可以操纵氧化物半导体的传输特性，并具有改进的性能和意想不到的功能。