Anneal-induced variations of the recombination characteristics in 2 MeV proton irradiated Si structures

Abstract

Comparative study of the carrier recombination and generation lifetime as well as reverse recovery durations, dependent on proton irradiation fluence and annealing regimes, has been performed on FZ silicon PIN diodes and wafer structures. The samples were irradiated by 2 MeV protons with fluences in the range of 7⋅10¹²–7⋅10¹⁴ p/cm². Carrier decay constituents and values of recombination lifetime have been evaluated by employing a microwave probed photoconductivity transient technique, while deep level spectra ascribed to variations of generation lifetime have been examined by exploiting capacitance deep level transient spectroscopy (DLTS). Variations of six DLTS peaks are examined under 24 h isochronal annealings in the range of temperatures from 80 to 320 ^∘C, to clarify threshold of annealing out of the specific traps. Fluence-dependent variations of the effective carrier recombination lifetime in wafer samples after isochronal annealing indicate a weak change in density of the recombination centres. The latter can be ascribed to cluster defects. Fluence-dependent variations of the reverse recovery time (RRT) in diodes after isochronal annealing imply the rearrangement of the recombination and trapping centres, probably within a space charge region (SCR) of clusters.
Keywords: carrier lifetime, reverse recovery time, microwave probed photoconductivity, deep level transient spectroscopy, proton irradiations, radiation defects
PACS: 61.72.J-, 61.82.Fk, 72.40.+w