ASPECTS OF REFLECTANCE ANISOTROPY SPECTROSCOPY FROM SEMICONDUCTOR SURFACES

There currently exists a wide range of powerful techniques for probing surfaces, mainly involving the use of electron or ion beams under hig h- or ultra-high-vacuum conditions. Recently there have been major eff orts to develop surface sensitive optical probes that have the inheren t advantage that they can be applied in more challenging environments such as in high pressures or under liquids and in real time. The most powerful of these techniques to emerge (similar to 10 years ago) is re flection anisotropy spectroscopy (RAS), which early on demonstrated it s ability to distinguish different reconstructions of GaAs(001) and to detect monolayer-growth-related oscillations similar to those routine ly obtained using reflection high-energy electron diffraction. This ar ticle describes some aspects of the development of the RAS technique s ince that time, focusing on our own theoretical and experimental studi es concerning the (001) surfaces of cubic semiconductors which have be en prepared by molecular beam epitaxy. These studies demonstrate that in surface chemistry, structure and electronic properties RAS has made powerful contributions to the study of such surfaces.