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The optimization of MBE growth conditions and layer structures for room temperature operation of 2.26 mu m AlGaAsSb/GalnAsSb laser structures is investigated. Index guided triple quantum well large optical cavity diode lasers with 64 mu m x 1000 mu m cavities and high reflection/antireflection coated facets reveal a cw output power of 350 mW at T = 280 K. An internal quantum efficiency eta(i) of 69 %, internal losses chi(i) of 7.7 cm(exp -1) and a threshold current density for infinite cavity length of 144 A/cm2 are obtained for this structure.

Strained single- and triple-quantum-well (SQW and TQW), large optical cavity GaInAsSb/ AlGaAsSb/GaSb laser diodes emitting at 2.26 mu m are investigated. Internal loss coefficients as low as 5 and 7.7 cm(exp -1) for the SQW and TQW, respectively, and relatively high internal quantum efficiencies of 65% (SQW) and 69% (TQW) were obtained. Extrapolated threshold current densities for infinite cavity lengths of 55 and 150 A/cm2 have been deduced for the SQW and TQW, respectively. These values scale very well with the number of QWs and are among the lowest reported for diode lasers in this wavelength range. A differential quantum efficiency as high as 50% and a total power efficiency of 23% were achieved at 280 K. The temperature dependence of the threshold current density revealed a high characteristic temperature of 110 K. Single-ended output powers of 240 mW in continuous-wave mode and exceeding 0.5 W in pulsed operation were obtained for a TQW laser with high-reflection/antireflection coated facets at 280 K, mounted substrate-side down.

The influence of strain in Ga(0.7)In(0.3)As(y)Sb(1-y) quantum wells (QWs) embedded in Al(0.24)Ga(0.76)As(y)Sb(1-Y) barriers on the photoluminescence (PL) emission wavelength and intensity has been investigated. The strain was adjusted by varying the As content in the QW and barrier layers. For As mole fractions in the (GaIn)(AsSb) QW layers between y = 0.25 and 0.05, the average strain perpendicular to the growth plane changes from (delta a/a) = 2.0 x 10(exp -3) to 10.4 x 10(exp -3) for lattice matched (AlGa)(AsSb) barriers. At room temperature, highest PL intensities are obtained for QW structures with a net compressive strain of (delta a/a) = 8.7 x 10(exp -3). In order to compensate the compressive strain in the QWs, strain-balanced laser core structures with barriers under tensile strain have been investigated. This was found to allow a reduction of the average strain in the laser core without shifting its emission wavelength. Ridge waveguide large optical cavity (LOC) laser diodes containing three compressively strained (Galn)(AsSb) QWs embedded between lattice matched (AlGa)(AsSb) barriers show room temperature cw laser emission at a wavelength of 2.26 mu m. For 64 mu m wide and 600 mu m long devices, a differential quantum efficiency of 43% and a threshold current density of 395 A/cm2 with a characteristic temperature of T(0) = 110 K are obtained.

The incorporation of As and In during MBE growth in (AlGaIn)/(AsSb) layers used for the fabrication of diode lasers in the 2.0-2.5 mu m wavelength range has been investigated. The As content was found to depend linearly on the beam equivalent pressure for As mole fractions between y = 0.05 and y = 0.20. Broad area A1GaAsSb/GaInAsSb singlequantum well laser diodes with quasi-cw output at room temperature at an emission wavelength of 2.03 mu m and a threshold current density of 515 A/cm2 for 1370 mu m long and 70 mu m wide devices have been fabricated. In order to shift the emission wavelength of the laser structures to longer wavelengths, the growth of lattice matched AlGaAsSb/ GaInAsSb laser core structures with different In and As mole fractions in the quantum wells has been investigated.