Aspects of reflectance anisotropy spectroscopy from semiconductor surfaces

Abstract
There currently exists a wide range of powerful techniques for probing surfaces, mainly involving the use of electron or ion beams under high- or ultra-high-vacuum conditions. Recently there have been major efforts to develop surface sensitive optical probes that have the inherent 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 ( years ago) is reflection anisotropy spectroscopy (RAS), which early on demonstrated its ability to distinguish different reconstructions of GaAs(001) and to detect monolayer-growth-related oscillations similar to those routinely obtained using reflection high-energy electron diffraction. This article describes some aspects of the development of the RAS technique since that time, focusing on our own theoretical and experimental studies concerning the (001) surfaces of cubic semiconductors which have been 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.