The estimation of radiation induced damages on nano-structured nuclear radiation detectors

Abstract

Silicon detectors have been widely used in high energy and nuclear physics experiments despite suffering severe radiation damage leading to degradationin the sensor performance. Such degradation include significant changes in detector efficiency, leakage current, bulk resistivity, space charge concentration, and free carrier trapping. In this work, neutron induced damages in siliconnanopillar detectors, the nanopillars dimensions being 10 nm diameter and 10 µm height wasanalyzed. The geometry was simulated in Geant4 and the nuclear interactions were evaluated by using ENDF/B-VII nuclear data library. Results showed that there are significant damages to the nano-pillars due to heavy charged particles and neutrons bombardment. Compared to the alpha (α) projectile, recoiled silicon produce more point defects with a higher yield. Neutrons also produce significant damage to the crystal lattice of Si nanopillars through point defects and it was also found that there is an increment in the production of 31P as the diameter of the nanopillar increases which further reduces the detector performance. The study demands optimization of pillar thickness for detection efficiency and damage. Hence with the detailed understanding of radiation effects on silicon devices combined with simulation techniques produces an impact on device design that predicts the behavior of specific devices when exposed to a radiation field of interest.