摘要
本文使用分子簇模型和原子交迭和电子离域-分子轨道(ASED—MO)方法,计算Al吸附在Si(111)面上不同位置的键长和键能(吸附能)。按照总能量最小原则,对铝吸附在硅表面层的顶位、中心位、再构中心位、迭位、再构迭位和桥位的不同位置,分别计称出Al—Si的键长为2.38、2.55、2.71、2.68、2.61和2.49×10^(-10)m;各位置对应的吸附能分别为0.72、0.37、0.40、0.01、1.02和0.62eV。另一方面,根据Al_3Si_(26)H_(26)分子簇的计算结果,得出3个铝原子吸附在Si(111)面上的最佳位置为相邻的双折(桥位)位置,同时由能量计算表明铝的复盖率为3/7单原子层。
Using the cluster models and the atom superposition and electron delocalization-molecular orbital (ASED-MD)method, the bond lengths and the binding energies for different adsonption positions of Al on Si(lll) surface are calculaed. Minimization of the total energies of the clusters with respect to the adatom from the surface silicon layer leads to Si-Al bond lengths of 2. 38, 2. 55, 2. 71, 2. 68, 2. 61,and 2. 49A for the atop, open, relaxed open, eclipsed, relaxed eclipsed and bridge, respectively. The corresponding binding energies are 0. 72, 0. 37, 0. 40, 0. 01, 1. 02 and 0. 62eV. On the other hand, on the basis of calculation of Al8Si26H26 cluster, it is proposed that there are the optimum configuration of three Al atoms on Si(111) surface' s neighbour twofold sites. A local coverage of 3/ 7 monolayer is also indicated by calculation of energy.
基金
国家自然科学基金
浙大研究生基金的资助
