Long-wavelength laser based on self-assembled InAs quantum dots in InAlGaAs on InP (001)

Abstract

Seven stacks of self-assembled InAs quantum dots (QDs) separated by 28nm thick InAlGaAs barriers were grown on InP (001) substrate by a solid-source molecular-beam epitaxy and were investigated by cross-sectional transmission electron microscopy and photoluminescence spectroscopy. Gain guided broad-area lasers with a stripe width of 75μm were fabricated by using the seven-stacked InAs QD layers with the InAlGaAs–InAlAs material system on InP (001). The lasing operation from InAs QDs was observed up to 260K and the characteristic temperature of the uncoated QD laser calculated from the temperature dependence of threshold current density was 377K for temperatures up to 200K, and 138K above 200K. The drastic decrease in the characteristic temperature above 200K was mainly related to the thermal behavior of carriers in QDs, and possibly the thermal coupling of the QDs to the wetting layer and the waveguide region.