DLTS MEASUREMENT OF ENERGETIC LEVELS, GENERATED IN SILICON DETECTORS

DLTS (deep level transient spectroscopy) measurements were performed o n irradiated Si detectors to record data on the energetic levels traps generated by neutrons. For moderate fluences (phi) of neutrons (phi < 10(12) n cm(-2)) electron and hole trap levels have been detected. Fo ur electron trap levels were found for both FZ (float zone) and MCZ (m agnetic Czochralsky) types of Si detectors but only two hole trap leve ls in FZ and one in MCZ detectors. This indicates that the type of sil icon has an influence on the traps generated by irradiation. From the values obtained for the relative concentration of E1 centers in MCZ an d FZ detectors, it results that the El centers are oxygen and not vaca ncy limited. Since the concentration of the E2, E3, and E4 levels are larger in FZ than in MCZ detectors, it may be assumed that the ''gette ring effect'' can control the formation of deeper traps. Filling pulse s were applied for various voltages and at the flat band filling volta ge, maximum ratio of N-t/N of the E1 center was achieved. This may ind icate that the concentration of E1 centers, near the p(+)-n interface, can be larger than in the rest of the junction.