Band‐Filling Model for Injection Luminescence at Higher Temperatures

An analysis is made of a simplified model of impurity band filling in heavily doped semiconductors at relatively high temperatures. The thermal energy kT is considered to be comparable with the characteristic energy parameter of the impurity band which describes the rate of decay of the density of state into the gap. Results of the analysis are applied to injection luminescence and are verified by a spectral study of the radiation from a number of diffusion and epitaxial GaAs diodes. Degenerate and non‐degenerate cases of the impurity band filling may be distinguished. The shifting peak in the former case and fixed thermal excited one in the latter case are expected. An unexpected result of the analysis is that the line‐width in the non‐degenerate case is temperature independent. This result is supported by the measurements. When the energy distribution of the density of states of the impurity band is Gaussian the line‐width is directly related to the dispersion of the distribution. Observed values of this dispersion reach 35 meV in heavily doped samples and exhibit a correlation with the donor concentration. Some other features of the model are also discussed.