CI在Si和Ge(111)面上的化学吸附

考虑了Si(111)和Ge(111)面吸附Cl的几何构形,本文采用集团模型,用电荷自洽的EHMO方法,对Si(111)和Ge(111)面,分别用能量极小的原则,确定了Cl的化学吸附位置。计算结果表明,对于Si(111)面,Cl是在顶位被吸附,形成共价结合,与实验结果一致。对于Ge(111)面,计算表明在顶位和三度开位上都能吸附Cl,与以前结论有一些不同,但本文认为偏振光电子谱的实验结果并不能完全排除Cl在Ge(111)面上顶位吸附的可能性。希望有其他实验能对Cl在Ge(111)面上的吸附作进一步的观察。此外,还计算了Cl在Si(111)面顶位上的吸附和它在Ge(111)面三度开位上的吸附时的状态密度,和实验结果进行了比较,相符甚好。 关键词：

CHLORINE CHEMISORPTION ON THE SILICON AND GERMANIUM SURFACE

The chlorine chemisorption geometry fcr both Si(lll) and Ge(lll) surface is considered. Previous theoretical calculations could not give the difference between Cl chemisorbtion on Si (111) and Ge(lll), which was shown by the effects observed in the photoemission with polarized radiation. In this paper the chemisorbed site is determined by the minimization of the total energy calculated by the charge density selfconsistent extended Huckel method. The present calculation shows that Cl adsorbs on the top site of Si (111) surface with covalent binding, which agrees quite well with experiments. While for the case of Ge, calculation shows that both the top site and three-fold site of Cl ehemisorption on the Ge(lll) surface are possible. Since the photoemission by p-polarized and s-polarized radiation did not differ too much for Cl on the Ge(lll) surface, it can not rule out the possibility of top adsorbed site for