ABSTRACT
The operation of the vast majority of modern electronic components can only be described through the band theory. The crystalline and near-crystalline forms of matter produce bands as described by the models presented in this chapter including the Kronig-Penney, tight binding, and k-p models. The bands produce an effective mass for the electron and hole, which can be many orders of magnitude smaller than the mass of the free electron. The effective mass has very important consequences for electrical conduction and the high-frequency performance of many devices. Purely crystalline materials do not have states in the energy bandgap. However, defects and doping do produce localized states within the gap that tend to trap the electrons and holes in a specific region of space and energy.
