Radiation damage measurements in room-temperature semiconductor radiation detectors

The literature of radiation damage measurements on cadmium zinc telluride (CZT), cadmium telluride (CT), and mercuric iodide (HgI2) is reviewed and in the case of CZT supplemented by new alpha particle data. CZT strip detectors exposed to intermediate energy (1.3 MeV) proton fluences exhibit increased interstrip leakage after 1010 p/cm2 and significant bulk leakage after 1012 p/cm2. CZT exposed to 200 MeV protons shows a two-fold loss in energy resolution after a fluence of 5×109 p/cm2 in thick (3 mm) planar devices but little effect in 2 mm devices. No energy resolution effects were noted from a moderated fission spectrum of neutrons after fluences up to 1010 n/cm2, although activation was evident. Exposures of CZT to 5 MeV α particles at fluences up to 1.5×1010 α/cm2 produced a near linear decrease in peak position with fluence and increases in FWHM beginning at about 7.5×109 α/cm2. CT detectors show resolution losses after fluences of 3×109 p/cm2 at 33 MeV for chlorine-doped detectors. Indium-doped material may be more resistant. Neutron exposures (8 MeV) caused resolution losses after fluences of 2×1010 n/cm2. Mercuric iodide has been studied with intermediate energy protons (10–33 MeV) at fluences up to 1012 p/cm2 and with 1.5 GeV protons at fluences up to 1.2×108 p/cm2. Neutron exposures at 8 MeV have been reported at fluences up to 1015 n/cm2. No radiation damage was reported under these irradiation conditions.