Thermoelastic stress in GaAs/AlGaAs quantum cascade lasers.

We have determined the shear stress associated with the temperature gradient in quantum cascade lasers operated in continuous-wave mode. This information was obtained as a function of the electrical power using a combination of microprobe photoluminescence and anti-Stokes/Stokes Raman measurements in ridge-waveguide GaAs structures mounted epilayer down to the heat sink. At electrical power densities in the order of ∼5 kW/cm(2), the strain in the cladding layers at the edges of the laser ridges reaches the critical value for the creation of misfit dislocations. Above 10-12 kW/cm(2), extended defect formation and eventual device failure are observed. [ABSTRACT FROM AUTHOR]