Developemtn of Low temperture Surface Electron Mictoscpy and its Application to Gas Adsotption on Surfaces.

表面电子显微术是近几年来发展起来的一种高空间分辨率的表面结构及其动态过程的研究方法。然而，已经在热表面上进行了研究。另一方面，低温表面是一个非常有意义的问题，人们对Si表面上的碱金属原子做了一些有趣的工作。本课题的目的是研制一种用于低温表面研究的特殊试样保持器，以研究气体在表面上的吸附，本课题的难点是试样保持器的研制。利用该装置可以对样品进行明显的冷却，并且可以对样品进行加热以进行清洁。利用蓝宝石晶体在50K附近是良好的导热体，在高温下是良好的绝缘体的特性，使样品在加热过程中保持隔热，并与冷却池保持良好的热接触。它和铜一样好。我们采用了我们自行研制的用于表面研究的REM（反射电子显微镜）保持器的设计。采用流动式冷却方法，其中不锈钢管冷却电极保持器的蓝宝石框架，并且电极可以通过框架和金属电极冷却。作为初步实验，我们研究了Si（001）和（111）表面在分子氧和原子氢作用下的表面结构和台阶结构的变化。在原子氢的情况下，形成所谓的Δ 7x7结构，但台阶形状不变。当氢原子从表面脱附时，它们不发生变化。在有氧存在的情况下，台阶形状不变，但当有SiO或SiO2形成时，台阶形状发生变化，该方法可用于固体气体吸附问题。

Surface electron mictosopy has been developed for these several years as a method which shows surface structures and their dynamic processes with high spactial resolution. However, studies have been done on hot surfaces. On the other hand. low remperature surfaces are very inreresting problems and some interesting works have been done on alkali-metal atoms on Si surfaces. The purpose of the present project is to make a special specimen holder for the study of low temperture surfaces and to study adsorption fo gasses on surcaes.The most difficult problem in the present project is to make a specimen holder. with which specimens can cooled for the obvservation and can be heated for cleaning. So that the speicmen should be thermally isolated during heating and it should thermally well contacted with the cooling reservoir, We used the characteristics of saphire crystal which is a good insulator at high temperatures byt is a good thermal conductor around 50K. It is as good as copper. We adopted a design of REM (reflection electron mictoscpy) holder which was developed by us for the studies of surfaces. Flow type cooling method is used where staianless tube cools a saphire frame of the specime holder and the specime can be cooles through the frame and the merallic electrode. Thus the heat floe during heating is refuced.As a preliminary experiment, we studied chanages of surface structues and step configurations when the Si(001) and (111) surface are exposed to molecular exygen and atomec hydrogen. In the case of atomic hydrogen, so called delta 7x7 structure is formed bur step shapes do not change. They do not change when the hydrgen atoms atoms desorb from the surfaces. In the case of oxygen step shapes do not change but on hearing SiO or SiO2 is formed and step configuration chenges.The method will be applide to solis gas adsoption problems.