MBE growth of low threshold GaSb-based lasers with emission wavelengths in the range of 2.52.7 μm

In this work, we present our approach towards the growth of active regions and cladding layers for GaSb based record low-threshold lasers emitting in the range of 2.52.7 μm. First, a study on Sb incorporation in the AlGaAsSb cladding layers and GaInAsSb QWs is presented as a function of growth temperature. A linear decrease in Sb incorporation was observed for both cases. Second, a choice of well-barrier material is presented. Here, the best results have been achieved with a GaSb/GaInAsSb combination, yielding a low-temperature (20 K) photoluminescence (PL) response with a very narrow full-width at half-maximum (FWHM) of 4.5 meV. The latter is followed by an investigation of active region degradation with increased annealing temperatures. The rapid degradation has been confirmed by PL and X-ray diffraction studies. Finally, device results are presented. Lasers show ultra-low CW threshold current densities (44 A/cm² at L→∞), in the wavelength range of 2.52.7 μm.