Improved high-temperature operation of InGaAs/AlGaAs LOC SQW diode lasers by incorporation of short-period superlattice quantum-well barriers
InGaAs/AlGaAs large optical cavity (LOC) single quantum well (SQW) lasers emitting at 980nm were grown incorporating an AlGaAs/GaAs short-period superlattice layer next to the quantum well in order to improve the carder confinement and thus high-temperature operation. Symmetric and asymmetric structures have been realized. High characteristic temperatures T0 above 300K between 20°C and 50°C operating temperature were measured for the symmetric structures without deterioration of the internal quantum efficiencies (> 90%) and low intrinsic losses (about 1cm-1). The improvement in the characteristic temperature is mainly attributed to the reduced thermionic emission of the carriers out of the quantum well due to the large effective barrier height of the short-period superlattice. Caused by the incorporation of the short-period superlattice the devices showed a higher series resistance, which could be lowered by switching to asymmetric structures. These asymmetric device s had unchanged high internal quantum efficiencies and low intrinsic losses but lower characteristic temperatures of about 250K.