The physics of transistors
Ernst Billig · British Journal of Applied Physics · 1952
Some of the fundamental concepts of the solid state which are required for an understanding of transistor action are discussed. The results of wave mechanics when applied to the solid state are outlined in simple non-mathematical language. The discrete levels of electron energy in single atoms and molecules become widened into energy bands in the solid. The large difference in the physical properties characteristic of such solids as metals, insulators, intrinsic and extrinsic semiconductors, can be accounted for by the width and relative position of their energy bands. When two different solids are brought into contact electrical potential barriers arise which pass electrons more freely in one direction than in the other. If electrons and holes are present simultaneously in a semiconductor, interaction occurs between them and this can be used to produce transistor action, i.e. to effect control over the flow of relatively large currents in a solid by means of weak optical or electrical signals.