Analysis of factors influencing the threshold current of Pb1–xSnxSe injection heterolasers

An analysis is made of the factors which influence the threshold current in PbSe/Pb_1–xSn_xSe injection heterolasers. These factors include the waveguide structure, electron confinement, inhomogeneity of the distribution of the gain across the thickness, nonradiative recombination at the heterojunctions and in the bulk, and temperature. The conditions are identified under which anomalies can be expected in the temperature dependence of the threshold current because of the influence of free carriers on the refractive index. The results agree with the experimental values of the threshold current density for a surface recombination velocity of ~2×10⁵ cm/sec and an internal quantum efficiency of ≤ 0.1.