In this work, we report the transport, defect state and electronic structure properties of unintentionally doped (UID) and Sn doped β-Ga2O3 homo-epitaxial thin films grown by molecular beam epitaxy (MBE) with electron density ranging from 2.1 × 1016 to 2.8 × 1019 cm−3. The UID film with an electron density of 2.1 × 1016 cm−3 exhibits a notable RT mobility of 129 cm2/Vs and a peak mobility of 900 cm2/Vs at 80 K, achieving the state-of-the-art level for MBE-grown Ga2O3 films. Temperature dependent Hall measurement reveal that Sn dopants have an activation energy of 56.7 meV. Synchrotron-based photoemission spectroscopy were further used to study insights into the evolution of electronic properties induced by Sn doping. An in-gap defect state was observed at the 1.5 eV above the valence band maximum for the Sn-doped Ga2O3 film. The in-gap state acts as self-compensating centers affecting the overall doping efficiency and mobility. Furthermore, photoemission spectroscopic study also reveals an upward surface band bending existing at the surface region of Sn doped Ga2O3 films. The identification of the in-gap state and surface upward band bending have significant implications for understanding the doping mechanisms in Ga2O3 and its electronic device applications.

中文翻译：

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MBE 生长的 Sn 掺杂 Ga2O3 同质外延薄膜的传输和电子结构特性


在这项工作中，我们报道了电子密度范围为 2.1 × 1016 至 2.8 × 1019 cm-3 的分子束外延 （MBE） 生长的无意掺杂 （UID） 和 Sn 掺杂 β-Ga2O3 同质外延薄膜的传输、缺陷状态和电子结构特性。电子密度为 2.1 × 1016 cm-3 的 UID 薄膜在 80 K 时表现出 129 cm2/Vs 的显着 RT 迁移率和 900 cm2/Vs 的峰值迁移率，达到了 MBE 生长的 Ga2O3 薄膜的最先进水平。与温度相关的霍尔测量表明，Sn 掺杂剂的活化能为 56.7 meV。基于同步加速器的光电子能谱进一步用于研究 Sn 掺杂诱导的电子特性演变的见解。在 Sn 掺杂 Ga2O3 薄膜的价带最大值以上 1.5 eV 处观察到间隙内缺陷状态。间隙内状态充当自补偿中心，影响整体掺杂效率和迁移率。此外，光电子能谱研究还揭示了 Sn 掺杂 Ga2O3 薄膜表面区域存在的向上表面带弯曲。间隙内状态和表面向上带弯曲的识别对于理解 Ga2O3 中的掺杂机制及其电子器件应用具有重要意义。