Electronic distribution in superlattice quantum cascade lasers

The electron population in the excited miniband of quantum cascade structur es with intrinsic superlattice active regions is extracted from the fine st ructure analysis of spontaneous interminiband electroluminescence spectra. At current densities typical of laser thresholds, the electrons injected in to the excited miniband of a (GaInAs)(6 nm)/(AlInAs)(1.8 nm) superlattice a re described by a nonequilibrium thermal distribution characterized by temp eratures T-e> 200 K, much higher than the lattice temperature T-L=15 K. (C) 2000 American Institute of Physics. [S0003-6951(00)04534-4].