Photoluminescence of heavily doped and compensated germanium

The photoluminescence of heavily doped and compensated (hdc) germanium is investigated in a wide range of the compensation degree, K ≈ 0.05 to 0.99. The energetic position of the emission band, its halfwidth, kinetics, and integral intensity are measured as functions of excitation intensity, temperature, and compensation degree. For strong compensation the changes are very striking. The obtained results are discussed in terms of a tunnel recombination of charge carriers localized in potential minima of a random potential relief, arising from the random distribution of charged impurities. It is shown that the predictions of the model for strong compensation are in good quantitative agreement with the experimental observations.