The Influence of Local Potential Fluctuations on the Low‐Temperature Radiative Recombination of Compensated Germanium

The luminescence of p‐Ge doped both with Ga and As impurities in the region of “intermediate” concentrations (10¹⁶ to 10¹⁸ cm⁻³) has been investigated. Potential fluctuations due to random distribution of impurities in a crystal were shown to be the main factor in compensated semiconductors affecting the spectrum of radiative recombination in this region of concentrations. Under conditions of low temperatures and low excitation nonequilibrium carriers localize in close‐to‐generation‐site potential wells. The character of their recombination therewith is similar to inter‐impurity recombination with the difference that the carriers are captured not by separate impurity atoms but by their aggregates. The distances between recombination carriers in this case are shown to depend on optimal dimensions of fluctuations rather than on impurity concentration. It has also been shown that at low temperature the energy distribution of non‐equilibrium electrons does not correspond to the density‐of‐states function in the impurity band of donors.