The interband photoluminescence spectra of InGaAsSb/AlGaAsSb quantum wells with different well widths have been experimentally studied. The dependence of the concentration of the charge carriers participating in the radiative recombination on the pumping intensity level was calculated. Results of theoretical calculations appeared to be in good agreement with the experimental relationship between the photoluminescence intensity at spectral maxima and the pumping intensity. The resonant Auger recombination involved two holes and one electron and caused a significant decrease in the charge carrier concentration was detected in one of the samples. Recommendations were made to increase the operating efficiency of semiconductor injection lasers at wavelengths of about 3 μm for suppressing the parasitic nonradiative Auger recombination.