Comparison of semi-insulating GaAs and 4H-SiC-based semiconductor detectors covered by LiF film for thermal neutron detection

Abstract In this contribution we have focused on comparison of spectroscopic properties of semi-insulating (SI) GaAs and 4H-SiC detectors of thermal neutrons fabricated at the Institute of Electrical Engineering SAS in Piesťany. 6LiF reactive film has been applied on Schottky contact as a convertor of thermal neutrons to detectable charged particles (tritons and α particles). Optimal thickness of the 6LiF film has been determined for front side irradiation using MCNPX code to be ca 25 μm. From the energies deposited by secondary charged particles in the active volume of a detector, corresponding responses have been calculated for different thicknesses of the 6LiF conversion layer. The calculated responses have been compared with those collected by measurements using thermal neutrons generated by 239Pu-Be neutron source. Thermal neutron spectra have been recorded by SI GaAs and 4H-SiC detectors using different 6LiF film thicknesses. Generally, in spite of limited spectroscopic performances of the studied detectors, two hills related to tritons (2.73 MeV) and α particles (2.05 MeV) are discernible in all spectra beside a noise peak positioned in the low energy region. The specific differences between SI GaAs and 4H-SiC detector response to thermal neutrons will be closely discussed in the paper.