Room-temperature irradiation of silicon doped with carbon

The temperature at which silicon is subjected to 'room-temperature' radiation damage is shown to determine the sequence of reactions undergone by the radiation products. For 'low'-temperature irradiation the production of interstitial carbon (C i ) atoms saturates rapidly with increasing radiation dose when only a small fraction of the carbon has been converted to C i atoms. 'High'-temperature irradiation produces spontaneous pairing of C i with substitutional carbon atoms. The carbon pairs trap further damage products to form a set of four perturbed centres. The transition from the 'low' to the 'high' temperatures occurs rapidly, e.g. between 40 and 60 degrees C.