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 (R-L=9.6 K/W) and the electrical power dependence of the electronic temperature (R-e=12.5 K/W) of Ga0.47In0.53As/Al0.62Ga0.38As1-xSbx quantum-cascade lasers (QCLs) operating at 4.9 mu m, in the lattice temperature range of 60-90 K. The low electron-lattice coupling constant alpha=10.4 K cm(2)/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(perpendicular to)=1.8 +/- 0.1 W/(K m), which is approximately three times larger than that measured in QCLs with GaInAs/AlInAs heterostructures.