用低能电子衍射研究ⅢA-ⅤA和ⅡB-ⅥA化合物(110)和(100)表面的弛豫

A STUDY OF IIIA-VA AND IIB-VIA COMPOUNDS AB(110)AND AB(100) SURFACE RELAXATION WITH LOW-ENERGY-ELECTRON DIFFRACTION

用低能电子衍射研究了ⅢA-VA和ⅡB-ⅥA化合物(110)和(100)表面的弛豫,发现当理论计算与实验符合得很好时其结构是:保持表面上A-B键长不变,用一个旋转角ω,使B原(离)子向外移动,A原(离)子向内移动,第一表面原子层间距d_1=0.610-0.810A[对ⅢA-VA(110)],0.536—0.825A[对ⅡB-ⅥA(110)1和0.633-1.060A[对ⅡB-ⅥA(1010),第二表面原子层间距d_2=1.300-1.610A[对ⅢA-VA(100)],1.430-1.700A[对ⅡB-ⅥA(110)]和0.820-0.930A[对ⅡB-ⅥA(1010),而第三表面原子层间距d_3=1.410-2·440A[对ⅢA-VA(110)],2.020-2.250A[对ⅡB-VIA(110)]和 1.910-2.440A[对ⅡB-VIA(1010)]。对此结构,弛豫率α是:0.24±0.02[对ⅢA-VA(110)],0.25±0.02[对ⅡB-VIA(1010)]和0.33±0.03[对ⅡB-VIA(1010)]。

We have studied the relaxation of I1IA-V1A and IIB-VIA compounds AB (110) and AB (1010) surfaces with LEED, and found that the best agreement between theory and experiment occurs in such a sturcture, in which the B atoms are tilted outward and A atoms are tilted inward, with an angle of rotation ω, keeping the bond length at surface A-B unchanged, and the first atomic surfaces layer distances d1 = 0.61 0-0.810A [for IIIA-VA (110)] , 0.536-0.825A [for IIB-VIA (110)] and 0.633-1.060A [for IIB-VIA (1010)] and the second surfaces atomic layer distances d2 = 1.300-1.610A [for IIIA-VA(ll0)] , 1.430-1.700A [for IIB-VIA (110)] and 0.820-0.930A[for IIB-VIA (1010)] and third one d3 = 1.410-2.440A [for 1I1A-VA (110)], 2.020-2.250A [for IIB-VIA (110)] and 1.910-2.440A [for IIB-VIA (1010)] . For this structure the relaxation susceptibility a are: 0.24±0.02Ffor IIIA-VA (110)], 0.25±0.02 [for IIB-VIA (110)] and 0.33 ±0.03 [for IIB-VIA (1010)].