Defects in p-type Cz-silicon irradiated at elevated temperatures



P-type Czochralski grown (Cz) silicon samples have been irradiated at room temperature (RT), 350, and 450 °C with 1.8 MeV protons to doses of 2×1012and 1×1013 cm-2 and analyzed by deep level transient spectroscopy (DLTS). The generation rate of interstitial carbon–interstitial oxygen (CiOi) increases with the irradiation temperature, suggesting less efficient annihilation of self-interstitials and mono-vacancies at elevated temperature. A defect located at ∼Ev+0.39 eV (Ev denotes the valence band edge) appears in the sample irradiated at 450 °C and also emerges at the expense of CiOi center in the sample irradiated at RT and subsequently heat-treated above 400 °C. The amplitude of this level is enhanced in the sample irradiated at 450 °C. By comparing the annealing behavior found by photoluminescence (PL) measurements and reported theoretical predictions, the ∼Ev+0.39 eV level is tentatively assigned to the interstitial carbon–oxygen dimer (CiO2i). In addition, other levels at ∼Ev+0.34 eV and ∼Ev+0.58 eV are observed in samples irradiated at 450 °C and RT with heat treatment in the range of 400-500 °C (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)