Density-of-states tail in heavily doped closely compensated semiconductors

The density of states in the gap of heavily doped closely compensated semiconductors is calculated taking into account the high-temperature correlation in the impurity distribution. It is shown that at small energies the density of states varies as exp(-5 epsilon ³2//8E_B¹2/kT₀) where E_B is the effective Bohr energy and T₀ is the temperature at which the impurity diffusion has been frozen out. At large energies the density of states is Gaussian. Numerical results are given for n-type GaAs.