Electronic Structure of Semiconductor Surfaces Studied by Photoelectron Spectroscopy

Abstract

Surface science goes back to the beginning of the 19th century. It was, however, only with the development of ultra high vacuum (UHV) technology in the 1960,s that reproducible experimental results from surfaces on the atomic scale could be obtained. At about the same time high speed computers appeared which made it possible to apply realistic computations of surface properties. The last decade ha8 seen a large progress in surface 8cience and the field is under rapid development. This is largely due to the continuous development of the experimental and the theoretical methods. Many basic properties of surfaces are now in principle understood. Much more research is however necessary to achieve detailed descriptions, in particular of complex systems such as interfaces, overlayers and multilayers. A coordinated interplay between theory and experiment is desirable to achieve an efficient progress. In this article we will illustrate the present understanding of semiconductor surfaces as achieved mainly by photoelectron 8pectroscopy using synchrotron radiation. We will choose three examples, namely results from (i) core level studies on a clean surface, (ii) valence band studies of a clean surface, and (iii) core level and valence band studies on an adsorbate system. Before presenting these results we will summarise the present understanding of the atomic and the electronic structure of crystalline semiconductor surfaces.