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

The growth conditions for InGaAs/InGaAsP/InP quantum dots (QDs) have been optimized and QDs of high luminescence efficiency and the room temperature operation of QD lasers emitting at ∼1.5 μm have been demonstrated. Lattice-matched InGaAsP (λ_g=1.0–1.1 μm) 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 1.13×10¹¹ 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 K, respectively. The room temperature PL peak intensity is about 50% that of a high-quality InGaAs/InP quantum well. Room temperature, pulsed operation at ∼1.5 μm has been achieved from broad area lasers with a 1 mm cavity length. Threshold current density per QD stack of ∼430 A/cm² is measured for the five-, seven-, and ten-stack QD lasers.