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研究了Si衬底上外延Ge薄膜中的应变。在超高真空化学气相沉积系统中生长Ge薄膜,采用高精度X射线衍射(XRD)和拉曼散射光谱检测薄膜的组份和应变。结果表明,外延薄膜的组份为纯Ge,没有Si的扩散;Ge薄膜中存在少量应变。Ge薄膜XRD峰位和拉曼散射峰位的偏移是由残余应变引起的。定量计算了热膨胀失配引入的张应变和晶格失配引入的压应变与Ge薄膜生长参数的关系,张应变随着生长温度的升高而近似线性增加,压应变随着生长厚度的增加按反比例减小,Ge薄膜最终应变状态由两者共同决定。理论计算值与实验结果吻合良好。
The strain in epitaxial Ge thin films on Si substrates was investigated. Ge films were grown in an ultra-high vacuum CVD system, and the composition and strain of the films were measured by high-precision X-ray diffraction (XRD) and Raman scattering spectroscopy. The results show that the composition of the epitaxial film is pure Ge, there is no diffusion of Si; Ge film has a small amount of strain. Ge film XRD peak position and Raman scattering peak position is caused by the residual strain. The relationship between the tensile strain introduced by thermal expansion mismatch and the compressive strain induced by lattice mismatch and the growth parameter of Ge thin film is quantitatively calculated. The tensile strain approximately increases linearly with the increase of the growth temperature. The compressive strain increases with the increase of the thickness Inversely reduced, the final strain state of Ge film is determined by both. The calculated results are in good agreement with the experimental results.