Room temperature operation of InGaAs∕InGaAsP∕InP quantum dot lasers

The growth conditions for $\mathrm{In}\mathrm{Ga}\mathrm{As}∕\mathrm{In}\mathrm{Ga}\mathrm{As}\mathrm{P}∕\mathrm{In}\mathrm{P}$ quantum dots (QDs) have been optimized and QDs of high luminescence efficiency and the room temperature operation of QD lasers emitting at $\sim 1.5\mu \mathrm{m}$ have been demonstrated. Lattice-matched InGaAsP $({\lambda }_g=1.0–1.1\mu \mathrm{m})$ was used as a barrier layer for the InGaAs QDs and the emission wavelength was controlled by the QD composition. High-density InGaAs QDs with an areal density as high as $1.13\times {10}^{11}{\mathrm{cm}}^{-2}$ have been grown. The integrated and peak intensity of the photoluminescence (PL) spectra at room temperature are as high as 25% and 10% of those at $10\mathrm{K}$ , respectively. The room temperature PL peak intensity is about 50% that of a high-quality $\mathrm{In}\mathrm{Ga}\mathrm{As}∕\mathrm{In}\mathrm{P}$ quantum well. Room temperature, pulsed operation at $\sim 1.5\mu \mathrm{m}$ has been achieved from broad area lasers with a $1\mathrm{mm}$ cavity length. Threshold current density per QD stack of $\sim 430\mathrm{A}∕{\mathrm{cm}}^2$ is measured for the five-, seven-, and ten-stack QD lasers.