IBIC analysis of SiC detectors developed for fusion applications

Abstract

In this work, we consider a 4H-SiC detector as a plasma diagnostic system for the detection of fusion-born alpha particles in future nuclear fusion reactors. A nuclear microprobe was used to locally irradiate micrometer-sized regions of the detector with 3.5 MeV He ions to fluences from 5 × 109 to 5 × 1011 cm-2. Ion Beam Induced Charge (IBIC) microscopy was employed to study its degradation in Charge Collection Efficiency (CCE) and energy resolution after irradiation. At high reverse-bias voltages, both parameters remain practically unaffected for fluences up to 1 × 1011 cm-2, while a significant deterioration of the spectroscopic performance was observed above 3 × 1011 cm-2. A theoretical drift-diffusion model, in combination with Shockley-Read-Hall recombination statistics, was used to obtain the holes lifetime from the fitting of the experimental CCE values measured at different reverse voltages. Holes lifetime was found to strongly decrease with increasing particle fluence, changing from 57 ns in pristine detectors to 0.2 ns after irradiation with a fluence of 1 × 1011 cm-2.