Energy Band Structure

Abstract

The compound semiconductors crystallize mostly in one of the four crystal structures, described in the preceding chapter. The forms of the energy bands, being determined by the crystal structure, are also basically of four types and these are described in this chapter. Information relating to the energy band structure is usually presented by plotting the energy of the electron, E, for values of the wave vector, k, limited to within the first Brillouin zone. We first introduce the concept of the Brillouin zone and describe its shape for the different crystal structures. The salient features of the energy bands for each structure are then discussed. It should be borne in mind that we are concerned with the extrema of energy bands when dealing with problems of transport. Hence although the detailed energy band diagrams are given for some of the important compounds, the discussion is mostly confined to the E-k relations for the extrema.