Energy Levels in Silicon

Abstract

A general review of energy levels in silicon covering information up to about 1972 appears in the book Deep Impurities in Semiconductors by A. G. Milnes (1973). Since that time much new information has been published and the purpose of this chapter is to review this progress. As new experimental techniques have been developed, many of the previously reported energy levels and capture cross sections have been revised, and a number of impurities have been found to exhibit more levels than previously suspected. Also, more has been learned about native defects and irradiation-produced levels in silicon. Deep impurity studies are of importance in connection with process­ induced defects that limit the yield of integrated circuits of increasing size, complexity, and resolution. Also, such defects can be harmful to the performance of large-area discrete devices such as power transistors, thyristors, and solar cells. Interest has continued in silicon extrinsic photoconductors for infrared detection with impurities such as indium, gallium, sulfur, and selenium (see, for example, Loh et al 1977). There has also been progress in the theoretical area, although in general energy levels of deep impurities in silicon still cannot be cal­ culated with any great success. The review begins with a brief look at some theoretical approaches.