The Metal-Semiconductor Interface

Interfaces between metal and semiconductor may be found almost everywhere in contemporary electronics. Often the metal is there just to serve as a contact to p-n junctions in the semiconductor. At other times, the metal-semiconductor interface itself performs essential electronic functions. Considerable scientific interest has been devoted to this latter situation since early in the century, as discussed by Welker (1) in the previous volume of this seriesl This early work led to a rather simple and classical model, in which an electrostatic barrier ~b arises within the semiconductor and produces the rectifying behavior. The barrier ~b is called the Schottky barrier or Schottky-Mott barrier in remembrance of that work. The prediction of ~b has proven not to be so simple, however, whether in terms of other phenomena (such as work functions) or terms of fundamental theories. It is to the various contemporary aspects of this problem that the present review is principally devoted. The most general treatments of the subject appear in the well-known 1957 book of Henisch (2) and in a more recent one by Rhoderick (3). Much of the current activity is reflected in the Proceedin~Ts of the Annual Conferences on the Physics of Compound Semiconductor Interfaces, usually published in the Journal of Vacuum Science and Technology, in addition to the standard physics journals. As for the chemical literature, there is but an occasional foray between the surface chemists and the practitioners of the metal-semiconductor interface: this in spite of the considerable emphasis on interface chemistry in recent discussions of the Schottky