摘要
利用常规的ＬＥＥＤ和高分辨率的ＳＰＡ－ＬＥＥＤ技术研究了标称（３３７）的Ｓｉ表面原子结构．经过反复的离子轰击（７００ｅＶＡｒ＋）和１３００Ｋ退火之后的这种表面形成稳定的（５，５，１２）晶面，即结构周期为（３３７）＋（２２５）＋（３３７）的有序的原子排列．这一事实说明：Ｓｉ（５，５，１２）是比Ｓｉ（３３７）更为稳定的晶面．ＬＥＥＤ和ＳＰＡ－ＬＥＥＤ图像证实，稳定的Ｓｉ（５，５，１２）表面为（２×１）原子再构，即沿［１１０］方向的周期是体内结构周期的两倍，而沿［６６５］方向的周期与体内结构周期相同．Ｓｉ（５，５，１２）－２×１表面的元胞面积为０．７６８×５．３４８ｎｍ２，这是至今所观察到的最大表面元胞之一．结合其它的实验结果，提出了一个Ｓｉ（５，５。
Abstract We have carried out conventional LEED and high resolution SPA LEED studies of nominal (337) surfaces of silicon.After repeated ion sputtering (700eV Ar +) and annealing at 1300K,the surface was dominated completely by a (5,5,12) structure,namely formed regular atomic arrangements with a structural unit of (337)+(225)+(337).This indicates Si(5,5,12) surface is more stable than Si(337).Both LEED and SPA LEED patterns showed that Si(5,5,12) surface has a 2×1 superstructure with a 2 fold period of the bulk terminated structure in the direction and a period of the bulk terminated structure in the direction.The Si(5,5,12) 2×1 surface has a unit cell of 0.786×5.348nm 2,which is one of the largest unit cells ever observed. Combining with other experiments, a modified reconstruction model has been proposed.
基金
国家自然科学基金
