Calculation of the Coulomb broadening of donor-acceptor pair emission in compensated semiconductors

The line shape of donor-acceptor pair luminescence bands in doped but parti ally compensated semiconductors exhibits a distinct broadening effect with increasing compensation ratio. We present a very sensitive Monte Carlo simu lation of pair band emission highly suitable for typical compensated materi als such as ZnSe:N, serving not only as a model material but being also of high-technological relevance. For low compensation, the line shape of the p air bands is calculated by taking into account the shift of the recombinati on energies due to charged impurities resulting in a very good agreement wi th the experiment. The model is perfectly applicable also to codoped ZnSe:N :Cl with Cl allowing for a precise control of the compensation ratio. By mo delling the line shapes and comparing with the experiment, the density of c ompensating impurities could be determined even to values as low as several 10(16) cm(-3). However, for high-compensation ratios, the model fails beca use relaxation between the excited donor-acceptor pairs is neglected.