Room-temperature continuous-wave lasing from stacked InAs/GaAs quantum dots grown by metalorganic chemical vapor deposition

We report on quantum dot (QD) lasers made of stacked InAs dots grown by metalorganic chemical vapor deposition. Successful growth of defect-free binary InAs/GaAs QDs with high lateral density ${\mathrm{(d}}_l{\text{⩾4×10}}^{10}\hspace{0.17em}{\mathrm{cm}}^{\mathrm{-2}})$ was achieved in a narrow growth parameter window. The room-temperature photoluminescence (PL) intensity is enhanced up to a factor of 3 and the PL peak width is reduced by more than 30% when a thin layer of ${\mathrm{In}}_{\mathrm{0.3}}{\mathrm{Ga}}_{\mathrm{0.7}}\mathrm{As}$ is deposited onto the InAs QDs. A QD laser with a single sheet of such InAs/InGaAs/GaAs QDs exhibits threshold current densities as low as 12.7 and $\text{181\hspace{0.17em}}{\mathrm{A/cm}}^{\mathrm{2}}$ at 100 and 300 K, respectively. Lasers with threefold stacked QDs show ground-state lasing and allow for cw operation at room temperature.