Surface etching of 6H-SiC (0001) and surface morphology of the subsequently grown GaN via MOCVD
Surface etching of 6H-SiC (0001) and surface morphology of the subsequently grown GaN via MOCVD
复制标题
6H-SiC (0001) 的表面蚀刻和随后通过 MOCVD 生长的 GaN 的表面形貌
DOI：
10.1007/s11664-000-0153-x
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发表时间：
2000
影响因子：
2.1
通讯作者：
J. Edgar
中科院分区：
文献类型：
--
作者：
Z. Xie;C. Wei;S. F. Chen;S. Jiang;J. Edgar
研究了6H-SiC（0001）衬底在H2、C2H4/H2和HCl/ h23种介质中蚀刻的表面条件与GaN涂层表面形貌的关系。在h2cl中蚀刻6H-SiC可以得到具有台阶和梯田的高质量表面，而在HCl/ h2cl中蚀刻可以产生带有许多凹坑和丘陵的粗糙表面，也可以产生类似于H2中蚀刻的光滑表面，具体取决于HCl浓度和温度。然后通过MOCVD使用低温GaN或高温AlN缓冲层将GaN涂层沉积在这些蚀刻基底上。衬底表面缺陷增加了生长在LT-GaN缓冲层上的GaN涂层上的“巨型”针孔（2-4µm）的密度和尺寸。在HT-AlN缓冲层上生长的样品上经常观察到小针孔（<100 nm），其密度随着表面质量的提高而降低。基体表面缺陷引起的氮化镓成核不均匀和岛状面生长速度缓慢是形成“巨型”针孔的原因，而小针孔则是由错配位错引起的。
The correlation between surface morphological properties of the GaN epilayers and the surface conditions of 6H-SiC (0001) substrates etched in H2, C2H4/H2, and HCl/H2was studied. Etching 6H-SiC in H2produced a high quality surface with steps and terraces, while etching in HCl/H2produced either a rough surface with many pits and hillocks or a smooth surface similar to that etched in H2, depending on the HCl concentration and temperature. The GaN epilayers were subsequently deposited on these etched substrates using either a low temperature GaN or a high temperature AlN buffer layer via MOCVD. The substrate surface defects increased the density and size of the “giant” pinholes (2–4 µm) on GaN epilayers grown on a LT-GaN buffer layer. Small pinholes (<100 nm) were frequently observed on the samples grown on a HT-AlN buffer layer, and their density decreased with the improved surface quality. The non-uniform GaN nucleation caused by substrate surface defects and the slow growth rate ofplanes of the islands were responsible for the formation of “giant” pinholes, while the small pinholes were believed to be caused by misfit dislocations.