Dependence of type II “W” mid-infrared photoluminescence and lasing properties on growth conditions

We have studied how the photoluminescence (PL) and lasing characteristics of mid-IR type II “W” $[{\mathrm{InAs/Ga}}_{\text{1−x}}{\mathrm{In}}_x{\mathrm{Sb/InAs/AlAs}}_y{\mathrm{Sb}}_{\text{1−y}}]$ structures depend on the molecular beam epitaxy growth conditions. The growth temperature that yields the highest PL intensities and narrowest PL lines is found to be in the ≈480–510 °C range, which is considerably higher than the temperatures used in previous type II antimonide laser growths. Also contrary to earlier reports is our observation that using migration-enhanced epitaxy to force an InSb-like interface bond type is detrimental to the laser performance. The PL intensity at 78 K is found to correlate closely with the PL intensities and linewidths at all temperatures, as well as the lasing linewidths, thresholds, and efficiencies. Even though the tested laser structures were grown at a nonoptimal lower substrate temperature of 425 °C, they nonetheless yielded much better morphology, better-resolved x-ray features, stronger PL intensities, narrower PL linewidths, lower lasing thresholds (<200 W/cm² at 78 K), lower internal losses (20 ns at 78 K) than any previous antimonide lasers grown on the present Riber 32P molecular beam epitaxy system.