Silicon vacancy-type defects in as-received and 12-MeV proton-irradiated (formula presented) studied by positron annihilation spectroscopy

Positron lifetime spectroscopy is used to detect vacancy-related defects in as-received and 12-MeV proton-irradiated (formula presented) crystals. We can infer from the temperature dependence of the lifetime spectra decomposition that neutral and negatively charged vacancy defects exist in crystals before and after proton irradiation at low fluence (formula presented) Neutral vacancies are detected after irradiation at high fluence (formula presented) Negatively charged (formula presented) silicon monovacancies with (formula presented) lifetime are detected at low temperature in as-received n-type (formula presented) and after irradiation at low fluence. Neutral (formula presented) divacancies associated with the (formula presented) lifetime are produced by irradiation and dominate the positron trapping at room temperature. In addition, different types of ionic acceptors are detected. One of them acts as a strong trapping center even at room temperature.