Divacancy profiles in MeV helium irradiated silicon from reverse I–V measurement

Abstract

The application of high-voltage reverse current to voltage characteristics for characterization of ultra-deep radiation defect profiles in ion irradiated silicon p-i-n diodes is presented. Theoretical analysis shows that monitoring of the reverse current gradient with increasing bias can give, in combination with Deep Level Transient Spectroscopy (DLTS) and Capacitance–Voltage (C–V) measurement, quantitative information about the distribution of generation defect centres with the highest emissivity. The method is subsequently used for characterization of deep-level profiles in p +pnn + power diodes irradiated by He 2+ ions with energies 11–22 MeV and fluences 2.5 × 10 9–1.2 × 10 10 cm −2. The results show that the method can non-destructively determine the concentration profile of divacancies, the dominant generation centre in helium irradiated silicon, in the depths of the device where application of other methods usually fails.