中文摘要：

在130-830K温度范围内,系统研究了Si（111）-√3×√3-Ag和Si（111）-3×1-Ag超薄膜重构表面的光学二次谐波的温度依赖性,分析了信号强度的变化和表面结构之间的关联.结果表明,对于Si（111）-3×3-Ag结构薄膜表面而言,在130K到320 K的温度范围内,表面光学二次谐波信号强度的变化中没有出现明显的跃变,反映出在这一温度范围内没有出现结构相变,与K.Sakamoto等人的光电子衍射实验结果一致.而对于Si（111）-3×1-Ag薄膜表面,二次谐波信号在200K到500K之间出现的台阶式变化可能反映了在500 K时Si（111）-3×1-Ag到Si（111）-6×1-Ag的结构相变.其结果对金属原子在半导体表面的吸附、金属超薄膜生长机理和纳米结构体系结构相变的研究具有一定的参考价值和实际意义.

英文摘要：

The temperature dependence of optical surface second-harmonic generation signal from Si（111）-√3×√3-Ag and Si（111）-3×1-Ag surfaces were studied with the temperature ranging from 130 K to 830 K.The relationship between the signal and surface structure has been discussed.In our experiments,no remarkable signal change reflecting phase transition of Si（111）-√3×√3-Ag has been observed from 130 K to 320 K,consistent with the photoelectron diffraction results of K.Sakamoto et al.For the Si（111）-3×1-Ag structure,the second-harmonic signals show step-changes at about 200 K to 500 K,which may reflect a phase transition from Si（111）-3 × 1-Ag to Si（111）-6 × 1-Ag at about 500 K.The result has practical significance in the study of metal atom adsorption on the semiconductor surface,the growth mechanism of metal ultrathin films and the phase transition of nanostructures.