20 YEARS OF SEMICONDUCTOR SURFACE AND INTERFACE STRUCTURE DETERMINATION AND PREDICTION - THE ROLE OF THE ANNUAL CONFERENCES ON THE PHYSICS AND CHEMISTRY OF SEMICONDUCTOR INTERFACES

During the two decades 1974-93, semiconductor surface structure determination has evolved into a routine tool. This rapid evolution resulted from the confluence of three factors: the development of new techniques (e.g., scanning tunneling microscopy) and the improvement of old ones (e.g., low-energy electron diffraction), greatly increased reliability of vacuum equipment and electronics, and orders of magnitude enhancement in the speed and cost effectiveness of digital computers. A critical role of the annual conferences on the physics and chemistry of semiconductor interfaces (PCSI) in this evolution was to focus the attention of researchers on surface and interface structure as the key measurable intermediary between electronic materials processing and the performance of the resulting devices. Studies of several important systems, e.g., the (110) cleavage faces and (100) molecular-beam epitaxy growth faces of zinc blende structure compound semiconductors, were driven by events reported at PCSI conferences. These conferences were instrumental in stimulating the development of theoretical models which could extrapolate between vacuum surfaces, for which structural data have become readily available, and semiconductor heterostructures, for which comparable data are only now beginning to appear. Because of this development, the insight developed for vacuum surfaces is currently being applied to the prediction of interface specific electronic properties of semiconductor heterostructures (e.g., band offsets in heterojunctions and Schottky barrier heights in epitaxical metal-semiconductor junctions). In this way the PCSI conferences have forged a fink between the surface science of semiconductors and the fabrication of microelectronic devices so that both evolve faster than either one would have otherwise. This article documents some specific examples of the nature and consequences of this process.