Abstract The temperature and concentration dependence is studied of the excess charge carrier's lifetime in Si doped with Ga, In and Sb. The elements listed do not show any significant influence on the recombination rate of the minority carriers. Trapping is observed in In-doped n-type silicon due to the hole capture by negatively charged In centers. The hole capture cross-section is equal approximately to 2 × 10 −16 cm 2 at 80°K and is but weakly temperature dependent. The electron capture cross-section of neutral In centers is 4 × 10 −22 cm 2 at 80°K and increases with decreasing temperature. Recombination radiation accompanying the electron capture by In atoms is studied quantitatively; the capture cross-section is shown to be determined by radiative transitions.