Dual-barrier GeSn quantum-well lasers with operation up to 150 K

GeSn/SiGeSn quantum wells (QWs) have been investigated for the development of GeSn-based lasers. Barrier/well configurations including GeSn/GeSn and SiGeSn/GeSn were grown and characterized to evaluate carrier confinement and collection efficiency. In our previous work, a dual-barrier design (SiGeSn barrier/GeSn barrier/GeSn well) exhibited improved carrier collection efficiency for a GeSn single QW structure compared with a single-barrier configuration; however, no lasing had been reported from dual QW devices to date. Here, we report lasing from a GeSn dual-barrier single QW structure up to 140 K, with a threshold of 67 kW/cm2 at 77 K, representing a substantial threshold reduction. In addition, a 4-QW laser employing the same dual-barrier design demonstrates a clearly reduced threshold of 50 kW/cm2 at 77 K and a slightly increased maximum operating temperature of 150 K. The lower lasing threshold is attributed to decreased average carrier concentration in each well that improves the differential gain and the reduced Auger recombination rate.