一种改进的运动学低能电子衍射和数据平均方法在Si(111)31/2×31/2-Al表面上的应用

本工作运用运动学低能电子衍射和数据平均方法(KLEED和CMTA),对Si(111)3^1/2×3^1/2-Al表面的原子结构进行研究。在大的参数范围内对T₄和H模型进行优化后,发现T₄模型与实验符合得更好(R_VHT=0.158),并且定出Al原子和最上面六层Si原子的位置。该模型中所有键长相对于体内值的变化都在5％以内。它与由全动力学低能电子衍射(DL-EED)分析得到的模型完全相符。这一成功的应用再次表明改进后的KLEED和CMTA方法是一种简单、实用、可靠的表面结构分析手段,用它对一些很复杂的表面进行结构分析已成为可能。 关键词：

APPLICATION OF THE IMPROVED KLEED/CMTA METHOD ON Si(111) 31/2×31/2-Al SURFACE

In this paper, we carried out an improved kinematic low energy electron diffraction and constant momentum transfer averaging (KLEED/CMTA) analysis of aSi(111)3^1/2×3^1/2-Al structure After a thorough optimization of the parameters, we came to the conclusion that T₄ model is the best, which gives an excellent agreement with experiment curves(R_VHT = 0.158). Atomic coordinates and bond lengths of the model have been determined for Al atoms and all Si atoms in the first six layers of the substrate. None of the bond-length deviations from the bulk value is larger than 5% and within an error bar of 0.05A, all of the parameters (except a lateral displacement) are consistent with the conclusion of DLEED. The successful application of the KLEED/CMTA method to such a complicated surface structure indicates strongly that the method is really very poweriul and reliable,and thus has great potential in surface structure analysis.