Coupled strained-layer InGaAs quantum-well improvement of an InAs quantum dot AlGaAs–GaAs–InGaAs–InAs heterostructure laser

Data are presented showing that, besides the improvement in carrier collection, it is advantageous to locate strain-matching auxiliary InGaAs layers [quantum wells (QWs)] within tunneling distance of a single-quantum-dot (QD) layer of an AlGaAs–GaAs–InGaAs–InAs QD heterostructure laser to realize also smaller size QDs of greater density and uniformity. The QD density is changed from ${\text{2×10}}^{10}/{\mathrm{cm}}^2$ for a 50 Å GaAs coupling barrier (QW to QD) to ${\text{3×10}}^{10}/{\mathrm{cm}}^2$ for a 5 Å barrier. The improved QD density and uniformity, as well as improved carrier collection, make possible room-temperature continuous-wave (cw) $\mathrm{QD}+\mathrm{QW}$ laser operation (a single InAs QD layer) at reasonable diode length (∼1 mm), current density 586 A/cm², and wavelength 1057 nm. The cw 300 K coupled InAs QD and InGaAs QW AlGaAs–GaAs–InGaA–InAs heterostructure lasers are grown by metalorganic chemical vapor deposition.