Huang Li, Liu Feng, Lu Guang-Hong, Gong X G
Surface Physics Laboratory and Department of Physics, Fudan University, Shanghai 200433, China.
Phys Rev Lett. 2006 Jan 13;96(1):016103. doi: 10.1103/PhysRevLett.96.016103. Epub 2006 Jan 3.
Based on first-principles calculations of surface diffusion barriers, we show that on a compressive Ge(001) surface the diffusivity of Ge is 10(2)-10(3) times higher than that of Si in the temperature range of 300 to 900 K, while on a tensile surface, the two diffusivities are comparable. Consequently, the growth of a compressive SiGe film is rather different from that of a tensile film. The diffusion disparity between Si and Ge is also greatly enhanced on the strained Ge islands compared to that on the Ge wetting layer on Si(001), explaining the experimental observation of Si enrichment in the wetting layer relative to that in the islands.
基于表面扩散势垒的第一性原理计算，我们表明，在300至900 K的温度范围内，在压缩的Ge(001)表面上，Ge的扩散率比Si高10(2)-10(3)倍，而在拉伸表面上，两者的扩散率相当。因此，压缩SiGe薄膜的生长与拉伸薄膜的生长有很大不同。与Si(001)上的Ge润湿层相比，在应变Ge岛中Si和Ge之间的扩散差异也大大增强，这解释了相对于岛中而言，润湿层中Si富集的实验观察结果。
