Experimental investigation of the lattice and electronic temperatures in Ga0.47In0.53As∕Al0.62Ga0.38As1−xSbx quantum-cascade lasers

The authors extracted the thermal resistance (RL=9.6K∕W) and the electrical power dependence of the electronic temperature (Re=12.5K∕W) of Ga0.47In0.53As∕Al0.62Ga0.38As1−xSbx quantum-cascade lasers (QCLs) operating at 4.9μm, in the lattice temperature range of 60–90K. The low electron-lattice coupling constant α=10.4Kcm2∕kA can be related to the beneficial effect of the high conduction band offset, peculiar to the GaInAs∕AlGaAsSb material system, on the electron leakage. The authors found an active region cross-plane thermal conductivity value k⊥=1.8±0.1W∕(Km), which is approximately three times larger than that measured in QCLs with GaInAs∕AlInAs heterostructures.