Fabrication and evaluation of bismuth tri-iodide radiation detectors

Abstract

Bismuth tri-iodide (BiI3) is a wide bandgap compound semiconductor and has high photon stopping power due to its high atomic number (Bi: 83, I: 53) and density (5.78 g/cm(exp 3)). In 1977, Guy A. Almantrout et al. reported carrier mobilities (electron: 680 cm(exp 2)/Vs and hole: 80 cm(exp 2)/Vs) and bandgap (1.72 eV) of BiI3 crystals. Because of its attractive characteristics, BiI3 is a very promising material for fabrication of radiation detectors that can be operated at room temperature. However, only a few investigations have been made on BiI3 radiation detectors. BiI3 has been studied as a radiation detector material. The radiation detectors were fabricated from BiI3 crystals grown by the Bridgman-Stockbarger technique. A peak for 5.48 MeV alpha-particles was recorded with the BiI3 detector with an energy resolution of 2.2 MeV FWHM. However, the detectors fabricated from the BiI3 crystals grown by this technique could not exhibit good energy resolutions. In this study, BiI3 crystals have been grown by the physical vapor transport. Radiation detectors have been fabricated from the grown BiI3 crystals and the detector performance has been characterized.