Strain adjustment in (GaIn)(AsSb)/(A1Ga)(AsSb) QWs for 2.3-2.7 mu m laser structures

The influence of strain in Ga0.7In0.3AsySb1 - y quantum wells (QWs) embedde d in Al0.24Ga0.76AsySb1 - 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 strai n perpendicular to the growth plane changes from (Delta a/a)(perpendicular to) = 2.0 x 10(-3) to 10.4 x 10(-3) for lattice matched (AlGa)(AsSb) barrie rs. At room temperature, highest PL intensities are obtained for QW structu res with a net compressive strain of(Delta a/a)(perpendicular to) = 8.7 x 1 0(-3). In order to compensate the compressive strain in the QWs, strain-bal anced laser core structures with barriers under tensile strain have been in vestigated. This was found to allow a reduction of the average strain in th e laser core without shifting its emission wavelength. Ridge waveguide larg e optical cavity (LOC) laser diodes containing three compressively strained (GaIn)(AsSb) QWs embedded between lattice matched (AlGa)(AsSb) barriers sh ow 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 4 3 % and a threshold current density of 395 A/cm(2) with a characteristic te mperature of T-0 - 110 K are obtained. (C) 2000 Elsevier Science B.V. All r ights reserved.