Si(111)理想、弛豫及2×1重构表面的声子谱研究

本文利用微扰的方法考虑了占据态与空态间的耦合对能带能量的影响,给出延展键轨道近似下半导体力常数的解析表达式.利用这些表达式求出Si(111)的理想、1×1弛豫及2×1Haneman模型重构表面的声子色散曲线及其表面振动的振幅分布.不同表面结果的比较显示弛豫及重构对表面声子性质具有决定性的影响.同时,分析表明Haneman的2×1表面重构模型不足以满意地解释有关实验结果.

INVESTIGATION OF SURFACE PHONONS AT IDEAL, RELAXED AND 2×1 RECONSTRUCTED Si(lll) SURFACE

Using the perturbation method to study the influence of the coupling between occupied states and empty states on the electronic band energy, we obtained analytical expressions for semiconductor force constant calculation within the scheme of extended band orbital approximation. The surface phonon dispersion curves and related vibrational amplititude distribution of Si(111) ideal, 1×1 relaxed and 2×1 reconstructed Haneman model surfaces are calculated by means of these expressions. The results for different surfaces show the important effects of surface relaxation and reconstruction on the properties of surface phonons. It is also shown that the Haneman model for Si(111)-2×1 reconstructed surface can not explain the experimental surface phonon measurement very well.