Extremely Low-Threshold Current Density InGaAs/AlGaAs Quantum-Well Lasers on Silicon

An InGaAs/AlGaAs quantum-well laser structure was grown on a silicon substrate by adopting a three-step grown thin (1.8 μm) and simple buffer layer. The whole structure was grown by metalorganic chemical vapor deposition. The material quality was characterized by transmission electron microscopy, photoluminescence spectra, and electrochemical capacitance-voltage profiler. It shows that the threading dislocation density and interface roughness are effectively reduced, and the active region's optical properties grown on a silicon substrate are comparable to that grown on a GaAs substrate. Broad stripe lasers have also been fabricated. The cavity length and stripe width are 1 mm and 15 μm, respectively. An extremely low-threshold current density of 313 A/cm2has been achieved under pulsed condition at room temperature. Meanwhile, the laser can operate under continuous wave condition at the temperature of 240 K. The above results make us more confident for realizing better performance of Si-based III-V semiconductor lasers by further improvement of the material growth method.