Structure of Ultrathin Native Oxides on III–Nitride Surfaces,ACS Applied Materials & Interfaces

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Structure of Ultrathin Native Oxides on III–Nitride Surfaces
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2018-03-20 00:00:00 , DOI: 10.1021/acsami.8b00845
J. Houston Dycus ₁ , Kelsey J. Mirrielees ₁ , Everett D. Grimley ₁ , Ronny Kirste _{1,

2} , Seiji Mita _{1,

2} , Zlatko Sitar _{1,

2} , Ramon Collazo ₁ , Douglas L. Irving ₁ , James M. LeBeau ₁

Affiliation

When pristine material surfaces are exposed to air, highly reactive broken bonds can promote the formation of surface oxides with structures and properties differing greatly from bulk. Determination of the oxide structure is often elusive through the use of indirect diffraction methods or techniques that probe only the outermost layer. As a result, surface oxides forming on widely used materials, such as group III-nitrides, have not been unambiguously resolved, even though critical properties can depend sensitively on their presence. In this study, aberration corrected scanning transmission electron microscopy reveals directly, and with depth dependence, the structure of ultrathin native oxides that form on AlN and GaN surfaces. Through atomic resolution imaging and spectroscopy, we show that the oxide layers are comprised of tetrahedra–octahedra cation–oxygen units, in an arrangement similar to bulk θ-Al₂O₃ and β-Ga₂O₃. By applying density functional theory, we show that the observed structures are more stable than previously proposed surface oxide models. We place the impact of these observations in the context of key III-nitride growth, device issues, and the recent discovery of two-dimensional nitrides.

中文翻译：

III-氮化物表面上的超薄天然氧化物的结构

当原始材料的表面暴露于空气中时，高反应性的断裂键会促进表面氧化物的形成，其结构和性质与体积大不相同。通过使用仅探测最外层的间接衍射方法或技术，常常难以确定氧化物的结构。结果，即使临界特性可以敏感地取决于它们的存在，也没有明确地解决在广泛使用的材料（例如III族氮化物）上形成的表面氧化物。在这项研究中，像差校正的扫描透射电子显微镜直接且深度依赖地揭示了在AlN和GaN表面上形成的超薄天然氧化物的结构。通过原子分辨率成像和光谱学，₂ ö ₃和的β-Ga ₂ ö ₃。通过应用密度泛函理论，我们表明观察到的结构比以前提出的表面氧化物模型更稳定。我们将这些观察结果的影响归因于关键的III族氮化物生长，器件问题以及二维氮化物的最新发现。

更新日期：2018-03-20

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