The Physics of Solids

Abstract

Before beginning a general discussion of electronic devices and the more complex aspects of semiconductors and other electronic materials, it is helpful to have an idea of their physics, especially their electronic structure. This chapter provides a partial review of the physics of solids. The nature of materials is determined by the interaction of their valence electrons with their charged nuclei and core electrons. This determines how elements react with each other, what structure the solid prefers, its optoelectronic properties and all other aspects of the material. The following sections describe the general method for understanding and modeling the energies of bands of electronic states in solids. A more detailed discussion of semiconductor bonding is provided in Chapter 5. 2.1 ELECTRONIC BAND STRUCTURES OF SOLIDS There are two approaches taken when considering how the weakly bound (valence) electrons interact with the positively charged atomic cores (everything about the atom except the valence electrons) and with other valence electrons in a solid. We will consider first the direct approach of solutions to the differential equations that describe the motion of electrons in their simplest form and the consequences of this behavior. This requires many simplifying assumptions but gives a general idea for the least complex problems. The second approach is to follow the electronic orbitals of the atoms as they mix themselves into molecular states and then join to form