High-Power AlGaAs/GaAs DH Stripe Laser Diodes on GaAs-on-Si Prepared by Migration-Enhanced Molecular Beam Epitaxy

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Abstract
We report on high-power low-threshold AlGaAs/GaAs double heterostructure (DH) stripe laser diodes on Si substrates by a hybrid growth of migration-enhanced molecular beam epitaxy (MEMBE) and metalorganic chemical vapor deposition (MOCVD). MEMBE-grown GaAs-on-Si had excellent surface morphology and showed much lower dislocation density than that of normal two-step MBE-grown or in situ annealed layers. The MEMBE growth and material characterization are described in detail. The 6-µm-wide oxide stripe lasers showed the highest peak power of up to 184 mW per facet reported to date, room-temperature pulsed threshold currents as low as 150 mA, and differential quantum efficiencies as high as 30% without mirror facet coating. The intrinsic threshold current density has been estimated to be about 2 kA/cm2 when taking current spreading and lateral diffusion effects into account. For comparison, the room-temperature pulsed threshold current density of 1.1 kA/cm2 was obtained for the broad-area DH laser diode fabricated on GaAs substrates in the same epitaxial deposition.