硅衬底上锗外延层的生长

Growth of Ge Epilayers on Si Substrates

利用超高真空化学气相沉积系统,基于低温Ge缓冲层技术,研究了Si衬底上高质量Ge外延层的生长。结果表明,低温Ge缓冲层的表面起伏较大,降低生长温度并不能抑制三维岛状生长。然而,低温Ge缓冲层的压应变几乎被完全弛豫,应变弛豫度达到90%以上。在90 nm低温Ge缓冲层上生长的210 nm高温Ge外延层,表面粗糙度仅为1.2 nm。Ge外延层X射线双晶衍射峰的峰形对称,峰值半高宽约为460 arcsec,无明显的Si-Ge互扩散。湿法化学腐蚀部份Ge外延层,测量位错密度约为5×10~5cm^(-2)。

Based on the low-temperature （LT） Ge buffer technique, the growth of high quality Ge epitaxial layer on Si substrates was researched by ultrahigh vacuum cheml vapor deposition. The results show that the surface of LT Ge buffer is extremely rough and it is unable to prohibit the formation of 3D islands just through lowering the growth temperature. However, the compressive strain of the low-tempera- ture Ge buffer was largely relaxed and the relaxation degree was above 90%. The surface roughness of the 210 nm high temperature Ge epitaxial layers on 90 nm LT Ge buffers is only 1.2 nm. The X-ray diffrac- tion peaks of Ge epitaxial layers are symmetrical and the full width at half maximum is about 460 arcsec, indicating no obvious Si-Ge inter-diffusion. The threading dislocation density is about 5 ×10^5cm^-2 after removal of partial Ge epitaxial layer by wet chemical etching.