InGaAs/GaAs/AlGaAs GRIN-SCH quantum-well lasers grown by solid-source molecular-beam epitaxy using CBr4 doping

Abstract

We have investigated the growth by solid-source molecular-beam epitaxy of InGaAs/GaAs/AlGaAs GRIN-SCH quantum-well lasers emitting near 940 nm, comparing carbon (from CBr4) to beryllium doping of the p-type material. The cladding layers, containing 45% aluminum, were grown at temperatures between 570 and 710 °C, while the single quantum wells were grown at 550 °C. The C- and Be-doped lasers exhibited similar characteristics for all substrate temperatures. For lasers with cladding layers grown at 570 °C, we obtained a relatively low threshold current density of 91 A/cm2 extrapolated to infinite stripe length for a 200-μm-wide stripe and an internal quantum efficiency as high as 95% with uncoated facets. At 690 °C, we obtained a threshold current density as low as 61 A/cm2, which compares reasonably well with the best reported value on near-(100) substrates of 45 A/cm2. In continuous-wave operation, we reached an output power of 575 mW/facet for a 200 μm×500 μm stripe with uncoated facets, and 49 mW/facet and a differential efficiency of 0.4 W/A per facet for a 5 μm×500 μm stripe.