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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 cryogenic Ge buffer layer technology, the growth of high quality Ge epitaxial layer on Si substrate was studied by using ultra-high vacuum chemical vapor deposition system. The results show that the surface of the low-temperature Ge buffer layer has a large surface undulation, and the decrease of the growth temperature does not inhibit the growth of the three-dimensional island shape. However, the compressive strain of the low-temperature Ge buffer layer is almost completely relaxed and the strain relaxation reaches over 90%. The 210 nm high-temperature Ge epitaxial layer grown on 90-nm low-temperature Ge buffer layer has a surface roughness of only 1.2 nm. Ge epitaxial layer X-ray double crystal peak diffraction peak shape symmetry, the peak full width at half maximum 460 arcsec, no significant Si-Ge mutual diffusion. Wet chemical etching part of the Ge epitaxial layer, measuring the dislocation density of about 5 × 10 ~ 5cm ~ (-2).