High-tenperature SIM observation under ion irradiation in order to modify surfaces in namscale

1.为了研究离子辐照硅表面退火过程的微观特征，我们研制了一套高温低能离子枪/扫描隧道显微镜（STM）联合系统。该系统使我们能够在高真空条件下同时进行原子分辨的高温STM观测和离子束辐照。利用该系统，我们成功地获得了Ar ~+单离子辐照高温Si（111）表面的STM序列图像。STM结果表明，单离子辐照引起的表面缺陷在尺寸和形状上有不同程度的变化，这可能是由于空位和间隙原子在衬底中的扩散、表面原子的扩散以及表面原子排列的各向异性等原因造成的。并成功地实现了0^+离子辐照下的STM实时观测。接下来的目标是掺杂剂离子辐照工艺。由于STM只观察表面信息，我们必须模拟体内和退火后的碰撞级联。采用第一性原理计算、分子动力学、蒙特-卡罗模拟等方法对所观察到的现象进行了研究。

1. A high-tenperature low-energy ion-gun/scanning-tunneling-microscope (STM) conbined system has been developed in order to clarify the microscopic aspects of annealing processes of ion-irradiated Si surfaces. This system enables us to perform atom-resolved high tenperature STM observation and ion beam irradiation simultaneously in ultrahigh vacuum conditions. Taking great advantage of this system, we have successfully obtained sequential STM images of high-temperature Si (111) surfaces irradiated with Ar' single ions. The STM results have shown that the surface defects induced by single ion irradiation show various changes in size and shape, which is considered to result from diffusion of vacancies and interstitial atoms in the substrates, diffusion of atoms on the surface, and from an anisotropic character of the surface atonic arrangement. And we succeed in real-time STM observation under 0^+ ion irradiation. Next target is dopant ion irradiation process.2. We have to simulate collision cascade inbulk and following annealing, because STM tipobserves surface information only. First principle calculation, molecular dynamics, Monte-Carlo simulation is applied to investigate the phenomenon we observed.