The temperature dependence of the free‐carrier concentration in germanium doped with the double acceptor Be has been investigated using the photo Hall‐effect technique and found to be strongly temperature dependent when the residual shallow impurities are closely compensated. Close compensation (NA&bartil;ND) of shallow levels was achieved by controlling the concentration of a beryllium–hydrogen acceptor complexA(Be,H) which is present in crystals grown under a H2atmosphere. This complex can be removed with high‐temperature annealing. An increase of up to two orders of magnitude in free‐carrier lifetime as a function of temperature is found to occur between 5 and 11 K in closely compensated material due to the population inversion of ionized centers created by optical pumping.