表面台阶对超高真空下Si(111)基片表面银原子吸附与重构的影响

Reconstruction of Ag Adsorbed on Stepped Si(111) 7×7 Surface

利用真空蒸发技术制备出了良好的Si(111)-3×3-Ag和Si(111)-3×1-Ag重构表面。通过低能电子衍射法和光学表面二次谐波法研究了两种类型切割角的单晶硅基片在超高真空银蒸镀过程中表面结构随衬底温度和蒸镀量的变化情况。vicinal样品产生的弱SinPout信号表明表面台阶的存在对Si(111)-3×3-Ag表面的成核生长过程有显著影响。低能电子衍射图片显示,500℃以上的高温下两种基片表面所形成的Si(111)-3×1-Ag重构分别为类单畴和三畴结构。类单畴和三畴结构Si(111)-3×1-Ag的光学表面二次谐波SinSout信号的一致性可能揭示了Si(111)-3×1-Ag结构中孪畴结构的存在。

Silver was deposited by vacuum evaporation on two different types of the stepped Si（111） 7×7 surfaces：called ＂just angle ＂（0.1°） sample and ＂vicinal＂（0.41°）sample,respectively.The impacts of Ag coverage,temperature and microstructures of the Si substrate on the well-ordered Ag atom arrangements were studied with low energy microscopy and optical surface second harmonic generation.The results show that the annealing temperature and density of steps significantly affect the reconstruction of the Ag atoms.In the case of vicinal sample,the nucleation and reconstruction of Si（111）-3×3-Ag depends strongly on the steps.At a substrate temperature higher than 500℃,the Si（111）-3×1-Ag reconstructed surfaces were found to be a near single-domain for vicinal sample,and a three-domain for the just-angle sample,respectively.We suggest that the consistency of the SinPout signal may indicate the existence of the twin domain of Si（111）-3×1-Ag.