SiO_2/Si(111)表面Ge量子点的生长研究

Growth of Ge Quantum Dots on SiO_2/Si(111) Surface

Si衬底用化学方法清洗后,表面大约残余1.0 nm厚SiO2薄膜。利用原子力显微镜(AFM)和反射高能电子衍射(RHEED)来研究温度和Ge蒸发厚度对在SiO2薄膜表面生长的Ge量子点的影响。实验结果表明,当衬底温度超过500℃时,SiO2开始与Ge原子发生化学反应,并形成与Si(111)表面直接外延的Ge量子点。在650℃时,只有Ge的厚度达到0.5nm时,Ge量子点才开始形成。

Ge quantum dots were grown on Si（111）,covered with 1.0 nm thick SiO2 film,by vacuum deposition. The Ge quantum dots were characterized with atomic force microscopy（AFM） and reflection high energy electron diffraction（ RHEED）. The results show that the sub- strate temperature and SiO2 thickness strongly affect Ge quantum dots growth. For instance, at a substrate temperature higher than 500 ℃, Ge atoms react with SiO2 and epitaxial nano Ge particles grow on Si（ 111 ）. However, at 650 ℃, Ge nano-particles do not form until Ge film thickness reaches 0.5 nm.