Long-wavelength PbSnTe-PbTeSe lattice-matched single-heterestructure lasers grown by LPE

Properties of Pb1 ¿ xSnxTe-PbTe1¿ySey lattice-matched single-heterostructure (SH) diode lasers grown on Pb1 ¿ xSnxTe substrates by liquid-phase epitaxy were studied for various compositions in the range 0.13<x<0.24, which corresponds to a wavelength range of 12 ¿m to 18.5 ¿m (at T = 20K). Threshold current density Jth was measured as a function of temperature from 10K to 140K, and was found to be comparable to that observed previously in PbSnTe-PbTeSe and PbSnTeSe-PbTeSe DH lasers. An external differential quantum efficiency of 1¿2% was measured in these lasers. The emission spectra of the SH lasers frequently show a single-mode structure for J<2Jth at high temperatures. Measurements of I/V characteristics carried out in these lasers suggest that tunnelling currents contribute significantly to the observed threshold current density. At high temperatures, characteristic temperatures To in the range 16.5 to 21 K were measured.