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MBE growth of mid-IR type-II interband laser diodes
MBE Wachstum von Typ II Interband-Laserdiode im mittleren Infrarot
We report on molecular beam epitaxial growth and characterization of InAs/GaInSb/InAs/AlGaAsSb type-II miniband-to-bound state W-lasers. Laser core structures were characterized using photoluminescence, high resolution X-ray diffraction and Raman spectroscopy to reveal the best growth conditions. The growth temperature for the laser core was varied in the range between 380 deg C and 460 deg C and found to be optimal at 420 deg C. Optimized laser active regions were embedded between 600 nm AlGaAsSb separate confinement layers which in turn were sandwiched between 1.5 µm thick n- and p-doped Al(0.85)Ga(0.15)As(0.07)Sb(0.93) cladding layers. The upper cladding was capped with a 100 nm p(exp +)-GaSb contact layer. The growth temperature of the upper separate confinement and cladding layer was varied between 470 deg C and 530 deg C to reveal the influence on laser performance. Laser emission is observed near 3.2 µm. Devices with uncoated facets, mounted substrate side down could beoperated up to a temperature of 185 K in continuous-wave (cw) mode. Single ended output powers of 144 mW in cw mode and 330 mW in pulsed operation were obtained for a 5-period diode laser structure with HR/AR coated mirror facets at an operation temperature of 110K.