Lead-tin telluride double-heterojunction laser diodes: Theory and experiment

Calculations of threshold current densities for lead-tin telluride double-heterojunction (DH) laser diodes are presented, in which the spatial distribution of the injected minority carriers and the critical level of minority carrier injection necessary for population inversion are considered. Excellent agreement between the predictions of this model and experimental data is obtained, which suggests that credible predictions of high-temperature performance can be made. The need to inject a critical level of minority carriers is shown to be the principal contribution to the threshold current density except at very low temperature and to lead to a rapid increase in threshold with increasing temperature. It is found experimentally that below 40 K the threshold no longer decreases with temperature; two possible explanations for this behavior are suggested.