用可调探深的电子能量损失谱研究Sn/Si界面

TUNABLE-SAMPLING-DEPTH ELECTRON ENERGY LOSS SPECTROSCOPY STUDIES OF Sn/Si INTERFACE

用可调探测深度的电子能量损失谱辅以俄歇电子能谱和低能电子衍射,研究Sn/Si系统的界面反应。结果表明:当Sn蒸镀量大于两个原子单层,退火温度由400℃到700℃,在Sn/Si(111)界面Sn与Si发生互混,形成几个原子层厚的Sn/Si互混层,该互混层的特征体峰在15.5eV。在相同温度范围退火,Sn/Si(001)界面无可察觉的互混,仍有Sn岛存在,长时间在550℃退火低能电子衍射图形上出现(113)小晶面的衍射斑。

In the present paper, the interfacial reactions at the interfaces of the Sn/Si system have been studied by means of tunable-sampling-depth electron energy loss spectroscopy (TELS) in conjunction with low-energy electron diffraction (LEED) and Auger electron spectroscopy (AES). It is found that, depending on the orientation of the silicon substrates, the interfacial reactions are qualitatively different. No intermixing of Sn with Si occurs at the as-deposited Sn/Si (111) interfaces and the Sn/Si (111) interfaces annealed at temperatures lower than 400℃. However, Sn intermixes with Si at the Sn/Si (111) interfaces annealed at temperatures between 400 adn 700℃, forming a Sn/Si intermixing layer with a maximum thickness of about 1nm. The bulk plasmon peak of this intermixed layer on the ELS curve is at 15. 5eV. No detectable intermixing of Sn with Si has been found at the Sn/Si (001) interfaces annealed at any temperature. Annealing at increasing temperatures only makes the homogeneous Sn layer to become islands, and the islands become smaller and eventually disappear at a temperature higher than 1000℃. A prolonged annealing at 550℃ gives rise to the appearance of (113) facets on the Sn/Si (001) surface, as shown by the 'moving spots' on the LEED pattern.