采用超高真空化学气相沉积(uHV-CVd)系统,用低温gE缓冲层技术在SI衬底上外延了张应变gE薄膜。扫描电镜(TEM)图表明SI基外延gE薄膜拥有低的位错密度,原子力显微镜(AfM)测试gE层表面粗糙度仅为1.2 nM。对SI基外延gE薄膜进行了不同温度下的退火,并用双晶X射线衍射(dCXrd)曲线和rAMAn谱进行表征。结果表明,SI基外延gE薄膜受到的张应变随退火温度呈线性增加,当退火温度达到850℃时SI和gE发生严重的互扩散,这种互扩散改变了室温Pl谱,影响外延gE薄膜特性。The thermal stability of strained Ge films on Si substrate is critical for applications in electronic and optoelectronic devices.In this paper,the Ge thin films under tensile strain were grown on Si substrate with low temperature Ge buffer layer by ultra-high vacuum chemical vapor deposition.The TEM image indicates that there are low threading dislocations in the top high temperature Ge layers.The root-mean-square surface roughness of the Ge epilayer is about 1.2 nm which was evaluated by atomic force microscopy.The thermal annealing effect on the Ge thin film properties was investigated by double crystal X-ray diffraction(DCXRD) and Raman measurement.The tensile strain in the Ge films increases linearly with the annealing temperature increasing from 650 ℃to 850 ℃.When the annealing temperature increases up to 850 ℃,serious Si-Ge intermixing is inferred from the X-ray diffraction rocking curves and Raman spectra,which modulates the room temperature photoluminescence spectrum significantly and affects the properties of Ge films.国家“973”计划资助项目(2007CB613404);教育部新世纪优秀人才计划资助项目(NCET-07-0724
