Abstract
The density of states in a heavily doped semiconductor is calculated using Feynman's path integral variational method. The case of low compensation is studied when the electron screening can be considered as linear. We have taken into account high-temperature correlations in the impurity positions arising from the Coulomb interactions between charged impurities, native point defects, and intrinsic and extrinsic electrons and holes at the temperature of the freezing of impurity diffusion. Variational expressions for the density of states are obtained in this case and their asymptotic forms at energies corresponding to the tail are found in two limiting cases. Numerical results for the electron and ionic screening radii, the Fermi energy and the r.m.s. potential energy as functions of electron concentration are obtained in the case of indium phosphide.