Improving CdMnTe Detector Performance by Adding 2% of Selenium

About 2% of selenium was added to CdMnTe (CMT) to reveal the role of selenium in CMT material used as a gamma-ray detector. The average etch-pit density (EPD) in a typical 2-in CdMnTeSe (CMTS) wafer was measured to be about
$8.3\,\, {}\times {}10^{3}$
cm−2 except for the edge regions, and the radial nonuniformity of the bandgap along the wafer was about 2-meV. The typical mobility-lifetime product of electrons and holes was evaluated to be
$3.06\,\, {}\times {}10^{-3}$
cm2/V and
$3.1\,\, {}\times {}10^{-4}$
cm2/V, respectively. The energy resolution of the 122-keV photo-peak for a Co-57 radioactive source with a planar CMTS detector was 5.2%, demonstrating a positive effect associated with adding dilute amounts of Se to CMT. The enhanced detector performance in a planar CMTS detector is attributed to an improved value of hole mobility-lifetime product in CMTS, which mitigates the adverse hole tailing effect found in CdZnTe (CZT) and CMT detectors.