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利用射频等离子体辅助分子束外延(RF-MBE), 通过在蓝宝石(0001)衬底上预先沉积金属Ga薄层的方法生长出了高质量的ZnO单晶薄膜. 这个Ga薄层的引入完全抑制了导致ZnO薄膜质量下降的旋转畴和倒反畴的形成. 反射式高能电子衍射(RHEED)原位观察以及高分辨X射线衍射(HRXRD)、透射式电子显微(TEM)和会聚束电子衍射(CBED)测试表明, 该薄膜具有很高的晶体质量和单一Zn极性. 详细讨论了Ga浸润层在ZnO的极性选择以及缺陷密度的减少等方面所起的作用, 并通过一个双层Ga原子模型分析了单一极性生长的机理.
High-quality ZnO single crystal thin films were grown by pre-depositing a thin layer of Ga on a sapphire (0001) substrate using radio frequency plasma-assisted molecular beam epitaxy (RF-MBE) The formation of rotating domains and inverted domains, which led to the degradation of the quality of ZnO thin films, were observed by RHEED, high resolution X-ray diffraction (HRXRD), transmission electron microscopy (TEM) and confocal electron beam diffraction (CBED) tests show that the film has high crystal quality and single Zn polarity.The effect of Ga wetting layer on the polarity selection of ZnO and the decrease of defect density is discussed in detail, The atomic model analyzes the mechanism of single polarity growth.