Orthorhombic gallium oxide (κ-GaO) is an ultra-wide bandgap semiconductor with great potential in new generation electronics. Its application is hindered at present by the limited physical understanding of the relationship between synthesis and functional properties. This work discusses the effects of growth method (metal-organic vapour phase epitaxy and molecular beam epitaxy) as well as annealing treatments in different atmospheres (O, H) on point defects in κ-GaO layers epitaxially grown on c-plane sapphire. Comprehensive experimental characterization by X-ray diffraction, photo current-as well as photoluminescence excitation spectroscopy, and X-ray photo electron spectroscopy is combined with first principles calculations of the point defects’ formation and complex-dissociation energies. We demonstrate that for κ-GaO the concentration of shallow and deep level defects can be sensitively controlled through annealing treatments at temperatures (T = 500 °C) well below the thermal stability threshold of this polymorph. In particular, our results suggest that hydrogen-related defects (, H-interstitials, Ga-vacancies—H complexes) play a key role in this process. While we provide direct exemplary implications of our results for the performances of κ-GaO based photodetectors, these findings are predicted to impact further application fields of κ-GaO, such as high electron mobility transistors or memory devices.

中文翻译：

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κ-Ga2O3 薄膜浅层和深层缺陷的工程设计：金属有机气相外延与分子束外延的比较以及退火处理的效果


正交晶系氧化镓（κ-GaO）是一种超宽带隙半导体，在新一代电子学领域具有巨大潜力。目前，由于对合成与功能性质之间关系的物理理解有限，其应用受到阻碍。本文讨论了生长方法（金属有机气相外延和分子束外延）以及不同气氛（O、H）下的退火处理对c面蓝宝石上外延生长的κ-GaO层点缺陷的影响。 X 射线衍射、光电流以及光致发光激发光谱和 X 射线光电子能谱的综合实验表征与点缺陷形成和复合解离能的第一原理计算相结合。我们证明，对于 κ-GaO，可以通过在远低于该多晶型物热稳定性阈值的温度 (T = 500 °C) 下进行退火处理来灵敏地控制浅层和深层缺陷的浓度。特别是，我们的结果表明，与氢相关的缺陷（H-间隙原子、Ga-空位-H复合物）在此过程中发挥着关键作用。虽然我们提供了我们的结果对基于 κ-GaO 的光电探测器性能的直接示范性影响，但这些发现预计将影响 κ-GaO 的进一步应用领域，例如高电子迁移率晶体管或存储器件。