In this article, we have established the expressions of the density of minority charge carriersand the recombination velocity at the back face of our sample.The effects of the base doping rate combined with the effects of temperature on the latter have been the subject of our study.Thus, we followed the evolution of the density of minority charge carriers and of the recombination velocity at the back face as a function of the thickness of the base for different base doping rate and for different values of the temperature.