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Improved threshold of buried heterostructure InAs/GaInAsP quantum dot lasers

: Franke, D.; Moehrle, M.; Sigmund, A.; Kuenzel, H.; Pohl, U.W.; Bimberg, D.


Journal of applied physics 109 (2011), No.8, Art. 083104
ISSN: 0021-8979
ISSN: 1089-7550
Journal Article
Fraunhofer HHI ()

The parameters for reducing the threshold current density of InAs/InGaAsP/InP quantum-dot (QD) lasers suitable for high temperature operation are studied. The structures were grown using metalorganic vapor phase epitaxy. Increasing the number of QD layers leads to a substantial improvement of the optical confinement and a markedly reduced threshold per dot layer in broad area devices. A reduction of the spacer thickness between the QD layers was not found to significantly affect device characteristics. Depending upon the device length, an optimum number of QD layers was deduced. Based upon optimized QD stacks, buried-heterostructure lasers with a medium device length emitting at 1.5 m were fabricated. Laterally single-mode devices show promising low threshold currents near 10 mA and good thermal stability with a characteristic temperature of 65 K up to 90 C.