Multi-stack InP/GaAsP quantum dot lasers on Si with high characteristic temperature

Monolithic integration of InP quantum dot (QD) lasers on silicon is essential for on-chip quantum technologies and biophotonics. We demonstrate 780-nm InP/GaAsP QD lasers monolithically grown on (001) Si with an improved characteristic temperature (T₀) of 125 K in the 20-50 °C range. By increasing the active-region stacking to five layers, the threshold current density was reduced to 0.86 kA/cm² with a thermal wavelength shift of 0.25 nm/°C. Comparative analysis with 3-layer counterparts on Si and devices on GaAs substrates indicates that the optimized 5-layer structure effectively enhances modal gain and consequently the thermal stability of Si-based near-infrared light sources. This work suggests that active-layer stacking is a feasible strategy for improving the thermal characteristics of InP QD lasers on Si.