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

低温表面电子显微镜的发展及其在表面气体吸附中的应用。

基本信息

批准号：
61880011
负责人：
YAGI Katsumichi
金额：
$ 7.81万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

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.

表面电子显微镜是近几年发展起来的一种以高空间分辨率显示表面结构及其动态过程的方法。然而，研究已经在炎热的表面上完成。从另一方面来说。低温表面是一个非常棘手的问题，人们已经对硅表面的碱金属原子做了一些有趣的工作。本课题的目的是制作一种用于低温表面研究和气体在表面吸附的专用样品夹持器，其中最大的难题是制作样品夹持器。用它可以冷却标本以进行观察，并可以加热以进行清洁。因此，在加热过程中，应注意隔热，并与冷库进行良好的热接触。我们利用了蓝宝石晶体在高温下具有良好的绝缘性的特点，在50K附近具有良好的导热性能。它和铜一样好。我们采用了我们开发的REM(反射电子微摆动)保持器的设计来研究表面。采用流动式冷却方法，即无支架冷却试件架上的蓝宝石框架，通过框架和金属电极冷却试件。作为初步实验，我们研究了Si(001)和(111)表面暴露在分子氧和氢气中时表面结构和台阶构型的变化。在原子氢的情况下，形成了所谓的Delta 7x7结构，但阶梯形状不变。当氢原子从表面解吸时，它们不会改变。在氧气的情况下，阶梯形状不变，但一听就形成SiO或SiO_2，并发生阶梯构型变化。该方法适用于Solis气体吸附问题。