SCANNING-TUNNELING-MICROSCOPY OF SEMICONDUCTOR SURFACES

The application of scanning tunnelling microscopy (STM) to semiconduct or surfaces is reviewed. After a brief description of theoretical mode ls for STM the experimental requirements are summarized. STM results w ill be shown and discussed for clean semiconductor surfaces (Si(111), Si(100), Si(110), high-index faces of Si, Ge and GaAs). Examples will be given for the more important reconstructions of these surfaces and for temperature dependent phase transitions, e.g., for the high-temper ature (7 x 7)/(1 x 1) transition of Si(111) and for the low-temperatur e c(4 x 2)/(2 x 1) transition of Si(100). The properties of steps will be described for Si(111) and Si(100). The study of adsorption and gro wth processes is one of the main fields in current STM work on semicon ductors and representative examples will be given for homoepitaxy, het eroepitaxy, cross-sectional studies, metal adsorption and adsorption o f small molecules which give rise to surface reactions. Finally, more recent applications such as manipulation of semiconductor surfaces, ba llistic-electron emission, potentiometry and electrochemistry will bri efly be reviewed.