Semiconductors

An excellent, short survey of the field of semiconductors and related topics is afforded by the compilation of papers presented at the AIEE Symposium on Electrical Properties of Semiconductors and the Transistor. The compilation consists of a qualitative discussion of theories of rectification and noise generation in metal-semiconductor contacts¹, internal and external photoeffects², the nature of conductivity³ and the transistor⁴. In Ref. 1, energy level diagrams are developed to describe the behavior of various metal-semiconductor contacts. Contacts are described between metal and n-type semiconductor, metal and p-type semiconductor, metal and semiconductor having surface states, and a contact having an artificial blocking layer. The Schottky theory is considered in some detail and numerical comparison made between experiment and theoretical predictions. Theories of the source of contact noise are summarized. The schematic mechanism for internal and external photoeffects is presented in Ref. 2. The primary and secondary photoconductive effects are discussed, including the properties of a germanium photoconductive cell. A comprehensive review is given of the use of photoelectric emission by Apker and associates to determine the distribution of energy states in metals and semiconductors. The majority of the papers referred to in Ref. 3 and Ref. 4 have been published separately during 1949 and will be described later in this chapter. In Ref. 3 numerical comparison is made between experiment and theory for conductivity in aluminum doped germanium and it is shown that both the impurity range and the intrinsic range can be accounted for. Some recent results are described of the effect of nucleon bombardment on the conductivity and ,the production of p-n junctions in germanium. A summary is given of the work on oxide semiconductors by Verwey and associates. Although Ref. 4 was published in 1950, it is mentioned here because it is a part of the compilation of Symposium papers. It summarizes a number of papers on the transistor. Reviews on semiconductors and rectifiers were written by Mott^5,6 and Tesyner⁷. A general qualitative disijussion of the nature of semiconductors was done by Andrews⁸. Haayman and Oosterhout⁹ wrote a short summary of the nature of semiconductors and discussed their practical application by the Philips Company.