Study of Si/Ge Strain-Controlled Atomic-Laver Super-Lattices

研究了锗衬底上硅和硅衬底上锗的异质原子层外延（ALE）方法。利用各种表面敏感性评价方法，阐明了ale的生长特性。在此基础上，制备了应变控制的Si/Ge原子层超晶格。主要结果如下：1。通过交替暴露DCS （SiH2Cl2）和原子氢（AH），在（100）和（111）表面建立了一个理想的1ML/循环生长速率的Si - ale程序。ale窗口为530oC ~ 610oC。利用表面形貌变化研究了微观生长动力学，在最佳ALE条件下获得了极平坦的生长表面，表面粗糙度增加小于0.1A。通过交替暴露DMG （GeH2(CH3)2）和AH，建立了在430 ~ 520℃的宽温度窗内生长速度为1ML/循环的Ge-ALE工艺。但由于生长膜中残留大量的C，当温度超过445℃时，生长表面平整度变差。GeH2Cl2似乎是平坦表面较宽温度窗口的理想源材料。用SiH4在Ge表面对Si进行了1ml厚的吸附。在这种1ml厚的Ge - Si结构上进行了Si ALE，制备了原子突变的Si/Ge异质界面。这种原子突变异质结构在550℃时热稳定。GTC （GeCl4）在Si表面交替暴露，形成1ml厚的Ge层。该结构是一种理想的无团簇、无混杂的1MLGe/Si异质结构。利用连续的Ge - 5自制了原子突变的Ge/Si异质界面。利用这些异质ALE方法制备了具有内部染色的Si7/Ge3原子层超晶格，并通过透射电镜观察了其微观精细结构。

Hetero atomic-layer epitaxy (ALE) methods have been developed for both Si on the Ge substrate and Ge on the Si substrate. And the ALE-growth characteristics were clarified by using various surface-sensitive evaluation methods. Base on these results, strain-controlled Si/Ge atomic layer super-lattices have been fabricated. The major results are listed below.1. By alternative exposure of DCS (SiH2Cl2) and atomic hydrogen, AH, a Si homo-ALE procedure has been established with an ideal 1ML/cycle growth rate on both (100) and (111) surfaces. An ALE-window was from 530oC to 610oC.Microscopic growth kinetics has been investigated by using surface morphology change, and the extremely flat grown surface with increased surface roughness of less than 0.1A was obtained under the optimum ALE conditions.2. By alternating exposure of DMG (GeH2(CH3)2) and AH, Ge-ALE procedure has been established with the 1ML/cycle growth rate over a wide temperature window from 430oC to 520oC.But due to large amount of residual C in the grown film, the grown surface flatness was deteriorated for temperatures more than 445oC.GeH2Cl2 seems the desired source material to the wider temperature window for the flat surface.3. 1ML-thick adsorption of Si has been done on the Ge surface by using SiH4. The atomically abrupt Si/Ge hetero interface has been fabricated by carrying out the Si ALE on this 1ML-thick Ge on Si structure. This atomically abrupt hetero structure was thermally stable up to 550oC..4. By alternating exposure of GTC (GeCl4) on the Si surface, 1ML-thick Ge layer was formed. This structure was concluded to be an ideal 1MLGe/Si hetero structure without clustering and intermixing. Atomically abrupt Ge/Si hetero interface has been fabricated by successive home ALE of Ge.5. By using these hetero ALE methods, Si7/Ge3 atomic-layer super-lattices with internal stain has been fabricated and their microscopically fine structures were observed by a transmission electron microscope.