Si_（1—x）Gex／Si应变层超晶格的结构稳定性研究

Structural Stability of SiGe/Si Strained-Layer Superlattices

利用喇曼散射谱研究了Ｓｉ１－ｘＧｅｘ／Ｓｉ合金型超晶格的结构热稳定性．对超晶格中折叠声学模和各类光学模的散射谱所作的定量分析表明：在８００℃下退火１０分钟，超晶格中由于原子互扩散引起的界面展宽已经非常严重；相比之下，晶格弛豫的大小与材料的生长条件有关．对较低温度（４００℃）下生长的超晶格，晶格弛豫量并不大，仅为１６％．同时，我们也从理论上证实并且在实验上观察到：折叠声学模的带隙随超晶格界面展宽而减小．

Abstract The structural thermal stability of SiGe/Si strained-layer superlattices has been investigated by Raman scattering spectroscopy. The quantitative analysis of Raman spectra from folded acoustic phonons and optical phonons in superlattices suggests that the interface width introduced by atom interdiffusion is comparable with the SiGe layer thickness under the condition of 800℃ 10-minutes thermal anneal.In contrast, the strain relaxation depending on the growth temperature of the supperlattice is only 16% for the sample grown at 400℃ under the same annealing condition.It is also observed that the gaps of the folded longitudinal acoustic modes near the Brillouin mini-zone edges shrink with interface wid,thas predicted by the theoretical calculation.