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

Seven stacks of self-assembled InAs quantum dots (QDs) separated by 28 nm 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 75 mum 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 260 K and the characteristic temperature of the uncoated QD laser calculated from the temperature dependence of threshold current density was 377 K for temperatures up to 200 K, and 138 K above 200 K. The drastic decrease in the characteristic temperature above 200 K 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. (C) 2004 American Institute of Physics.