The performance simulation of the LiH-SiC-based Fast Neutron Detector for harsh environment monitoring using Geant4 and TCAD

Abstract

In this work, Lithium Hydride (LiH) and Silicon Carbide (SiC) based sensor for fast neutron detection has been reported for the first time. LiH is used as a hydrogenous converter material for converting neutrons to charged particles (recoil protons) and wide band-gap semiconductor material SiC is employed as a charged particle sensing detector in the form of a Schottky Barrier Diode (SBD). Geant4 Monte-Carlo simulations have been performed for the optimization of the LiH converter layer thickness for different mono-energetic neutron sources as well as Am-Be standard neutron source. The optimization of LiH thickness is essential to attain the maximum neutron detection efficiency. The simulation study has revealed that the maximum neutron detection efficiency of ∼ 0.1% can be achieved at ∼800μm thickness of LiH for the Am-Be neutron source. Furthermore, a device simulation software (Silvaco TCAD) has been utilized to investigate the radiation-induced effects on the electrical characteristics of a SiC-based SBD detector. The gamma and neutron irradiation induced damage model has been developed from the experimental deep level defects information reported in the literature for the TCAD simulation study. The effects on different device parameters viz., ideality factor, Schottky barrier height, series resistance, built-in-potential, effective carrier concentration, image force lowering, carrier removal rate, etc., due to 60Co-gamma (dose=100 Mrad) and 1 MeV equivalent neutron irradiation (fluence up to 1016 neutrons/cm2) have also been reported. The 1 MeV equivalent neutron fluence is the fluence of 1 MeV neutrons producing the same damage in a detector material as induced by an arbitrary particle fluence with specific energy distribution. This model will be helpful in predicting the performance and behavior of the SiC-based devices which are subjected to heavy irradiation. The study reveals that the effect on the electrical characteristics of SiC-based SBD detectors is tolerable up to the fluence of 1015 neutrons/cm2 at room temperature, but preventive measures must be adopted to reduce the leakage current at elevated temperatures.