DLTS spectra of silicon diodes with p+-n-junction irradiated with high energy krypton ions

Abstract

p+-n-Diodes have been studied. The diodes were manufactured on wafers (thickness 460 µm, (111) plane) of uniformly phosphorus doped float-zone-grown single-crystal silicon. The resistivity of silicon was 90 Ohm cm and the phosphorus concentration was 5·10^13 cm^-3. The diodes were irradiated with 250 MeV krypton ions. The irradiation fluence was 10^8 cm^-2. Deep-level transient spectroscopy (DLTS) was used to examine the defects induced by high energy krypton ion implantation. The DLTS spectra were recorded at a frequency of 1 MHz in the 78–290 K temperature range. The capacity-voltage characteristics have been measured at a reverse bias voltage from 0 to -19 V at a frequency of 1 MHz. We show that the main irradiation-induced defects are A-centers and divacancies. The behavior of DLTS spectra in the 150–260 K temperature range depends essentially on the emission voltage U_e. The variation of U_e allows us to separate the contributions of different defects into the DLTS spectrum in the 150–260 K temperature range. We show that, in addition to A-centers and divacancies, irradiation produces multivacancy complexes with the energy level E_t = E_c - (0.5 ± 0.02) eV and an electron capture cross section of ~4·10^-13 cm^2.