室温下Ge(111)表面原子的协调运动

用扫描隧道显微镜观察了Ge(111)表面的由快速降温至室温而保留下来的中温相.发现除了单个Ge增原子的扩散运动外,主要的运动是发生在畴界上的Ge增原子列的开环和闭环协调运动.从实验上证实了这种最近引起很大实验和理论兴趣的运动方式.通过观察又提出了有待进一步实验和理论研究的问题.

CONCERTED MOTION OF Ge ADATOMS ON THE MODERATE TEMPERATURE PHASE OF THE Ge(111) SURFACE

In the present paper the moderate temperature (MT) phase of the Ge(111) surface, which was obtained by quenching the Ge(111) sample from about 300 1C to room temperature, has been studied by means of ultra-high-vacuum scanning tunneling microscopy (STM) . It has been found that in addition to diffusion of individual Ge adatoms, the most prominent feature of the MT phase is the concerted motion of Ge adatoms along the walls of the 2×2 domains. The moving adatoms may form either open strings or closed loops. Such concerted motion of Ge adatoms on the Ge(111) surface was predicted previously and has been of much theoretical interests, recently. However, this is the first experimental observation of such motion. Our study shows that the motion is not a result of STM tip interference and that it is always along the <011> directions. On the basis of our STM observations as well as the results of the recent theoretical works some discussions on the characteristics of the concerted motion are given.