溅射沉积自诱导混晶界面与Ge量子点的生长研究  

Growth of Ge quantum dot at the mix-crystal interface self-induced on the ion beam sputtering deposition

作　　者：熊飞[1,2] 潘红星[1] 张辉[2] 杨宇[1] 

机构地区：[1]云南大学工程技术研究院,昆明650091 [2]昆明理工大学光电子新材料研究所,昆明650093

出　　处：《物理学报》2011年第8期711-722,共12页Acta Physica Sinica

基　　金：云南省应用基础研究基金(批准号:2008CC012;2009CD003);云南省教育厅科学研究基金重点项目(批准号:09C008);云南大学科研基金(批准号:2009E28Q)资助的课题~~

摘　　要：在不同的沉积温度下采用离子束溅射技术,在Si基底上生长得到分布密度高、尺寸单模分布的圆顶形Ge量子点.研究发现:随沉积温度的升高Ge量子点的分布密度增大,尺寸减小,当沉积温度升高到750℃时,溅射沉积15个单原子层厚的Ge原子层,生长得到高度和底宽分别为14.5和52.7nm的Ge量子点,其分布密度高达1.68×1010cm-2;Ge量子点的形貌、尺寸和分布密度随沉积温度的演变规律与热平衡状态下气相凝聚的量子点不同,具有稳定形状特征和尺寸分布的Ge量子点是在热力学平衡条件限制下表面原子动态演变的结果.拉曼光谱证实,高能的表面原子在溅射生长过程中形成晶态和非晶态共存的Ge/Si混晶界面,溅射原子在混晶边界优先形核是获得高密度的自组装Ge量子点的重要原因.Ge量子点密集生长导致量子点之间的弹性作用增强,弹性排斥促使表面原子沿高指数晶面生长,使得在高温下采用离子束溅射的方法容易获得高宽比大、尺寸小、分布均匀的Ge量子点.The dense domes of Ge quantum dots on Si （001） substrate with a monomodal morphology distribution are deposited at different temperatures by ion beam sputtering （IBS）. The areal density of the Ge quantum dots is observed to increase with elevating temperature, but the dots size to decrease. As the deposition temperature increases to 750 ℃ , the smaller Ge quantum dots each with a height of 14.5 nm and base width of 52.7 nm are obtained by sputtering 15 monolayer Ge coverage, and the dots areal density is up to 1.68 × 10^10 cm^-2 at the same time. Thus the evolution of Ge quantum dot prepared by IBS is very different from that by vapor deposition at thermal equilibrium condition. The stable shape and the size distribution are demonstrated to result from the kinetic behavior of the surface atoms which is restricted by the thermodynamic limitations. A mix-crystal interface including amorphous and crystal components is revealed by Raman spectrum, and this special interface is demonstrated to contribute to the high density of Ge quantum dots, since the boundaries between the two different components can provide more preferential centers for the nucleation. As the density increases at high deposition temperature, the elastic repulsion between islands is enhanced, resulting in the surface atoms growing along the orientation of high index during the IBS deposition, and inducing the increase in aspect ratio and the reduction in island size.

关 键 词：GE量子点 离子束溅射沉积 表面原子行为 混晶界面 

分 类 号：O471.1[理学—半导体物理]