MOVPE-grown AlxGa1−xAsyP1−y strain compensating layers on GaAs

We demonstrate the substitution of Al0.85GaAs layers, used as claddings in edge-emitting diode lasers, with tensile strained Al0.85GaAs0.96P layers to reduce the room temperature wafer bow. Monitoring of the in-situ curvature change during growth and cool down is used for optimization of strain compensation. The onset of partial relaxation during growth caused by too high accumulated tensile strain is seen in in-situ transients of the wafer curvature and thus thickness and composition of the AlGaAsP layer can be optimized. Knowing the limits we finally propose and demonstrate a strain-compensation scheme for a two-stage diode laser which reduces room temperature curvature by Δκ=38km−1.

► Strain-compensation is achieved by replacing AlGaAs claddings in diode lasers with AlxGa1−xAsyP1−y. ► The phosphorus mole fraction is determined with HR-XRD using AlxGa1−xAsyP1−y test samples. ► In-situ curvature measurements are used to evaluate the strains during growth. ► The small compressive strain of Al0.85GaAs-on-GaAs at a temperature of 702 °C can be compensated. ► A curvature reduction of 38 km−1 for a two-stage laser diode is demonstrated.