From a fundamental transport formulation it is demonstrated that in heavily doped regions, only two independent parameters control the transport and recombination of minority carriers. The extraction of the minority carrier lifetime, diffusion coefficient, or bandgap narrowing is therefore impossible from DC measurements only. At least one additional AC measurement is necessary. The reported experimental data in the literature are critically revisited. When the published data are interpreted in terms of the original measurements a comprehensive picture appears, with surprising agreement among authors. Modeling of heavily doped regions in devices is shown to be possible, and good predictions of the emitter saturation current are demonstrated.