The density of states is required as the first step in determining the carrier concentrations and energy distributions of carriers within a semiconductor. Integrating the density of states function, g(E), between two energies El and E2 tells one the number of allowed states available to electrons in the cited energy range per unit volume of the crystal. In principle, the density of states could be determined from band theory calculations for a given material. Such calculations, however, would be rather involved and impractical.