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采用离子束溅射技术,通过改变Ge的沉积量,在n型Si(100)衬底上自组装生长了一系列Ge量子点样品.利用AFM和Raman光谱对样品表面形貌和结构进行表征,系统地研究了Ge量子点形貌、密度、尺寸大小以及Ge的结晶性和量子点中组分等随Ge沉积量的演变规律.结果表明:Ge层从二维薄层向三维岛过渡过程中,没有观察到传统的由金字塔形向圆顶形量子点过渡,而是直接呈圆顶形生长;且随着Ge沉积量的增加,量子点密度先增大后减小,Ge的结晶性增强同时Ge/Si互混加剧,量子点中Si的组分增加.
A series of Ge quantum dot samples were self-assembled and grown on an n-type Si (100) substrate by ion beam sputtering, and the surface morphology and structure of the sample were characterized by AFM and Raman spectroscopy. The morphologies, densities and sizes of Ge quantum dots as well as the crystallinity of Ge and the evolution of the composition of Ge with the deposition amount of Ge were systematically studied. The results show that the evolution of Ge layer from two-dimensional thin layer to three- , The transition from the pyramidal to the dome-shaped quantum dots is not observed, but the dome-shaped growth is directly observed. With the increase of Ge deposition, the quantum dot density first increases and then decreases, and the crystallinity of Ge increases At the same time, the intermixing of Ge / Si aggravates and the composition of Si in quantum dots increases.