Continuous wave (cw) operating temperature of 223 K was achieved with molecular beam epitaxy grown separate confinement buried heterostructure (SCBH) PbTe diode lasers with PbEuSeTe electrical and optical confinement layers. This is the highest cw operating temperature reported for midinfrared diode lasers. The active region of the SCBH diode lasers varies laterally to form a crescent-shaped waveguide with a maximum thickness of 0.15 μm and a lateral width of 2 μm. Exceptionally low threshold currents of 102 mA at 200 K, 166 mA at 210 K, and 249 mA at 215 K were measured.
Buried-heterostructure tunable PbEuSeTe/PbTe lasers were fabricated using a two-stage molecular beam epitaxy growth procedure. Improvements in the processing technique yielded lasers that show performance characteristics significantly better than those reported previously. A continuous wave (cw) operating temperature of 203 K was realized, which is the highest cw operating temperature ever reported for lead-chalcogenides diode lasers. This laser exhibited exceptionally low-threshold currents of 1.4 mA at 90 K and 43 mA at 160 K with single-mode operation for injection currents up to 30Ith and 0.18 mW power at 100 K. The usefulness of the laser, when operating cw at 200 K, was demonstrated by the ability to perform high-resolution spectroscopy of a low-pressure CO2 gas sample.
The phase equilibria data necessary for growing solid compounds of Pb1−xsSnxsSe1−ys Teys lattice matched to PbSe from melts consisting of (Pb1−xLSnxL)1−z (Se1−yLTeyL)z are presented. Liquidus data for values of xL from 0% to 40% and yL from 0% to 40% for temperatures between 450 and 540 °C are also presented. The influence of tellurium on the liquidus temperature is shown to be negligible at least for yL less than 40%. A crossover in the liquid-solid tie lines of tin, xs vs xL, for layers grown at 650 and 450 °C is observed at xL equal to 14%. The liquid-solid tie-line data for tellurium, ys vs yL, show a low segregation coefficient relative to selenium for yL less than 40%, thus explaining tellurium’s limited influence on the liquidus temperature. The lattice-matching conditions for xL =5%, 10%, and 20% are yL =16.4%, 25%, and 33.5%, respectively. A significant lattice-pulling effect is observed for the 5% tin case and is expected for the 10% and 20% tin cases. This effect, along with the low relative segregation coefficient for tellurium, makes it possible to easily grow lattice-matched layers of PbSnSeTe on PbSe by liquid phase epitaxy.
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