Purification, crystal growth and detector performance of TlBr

Abstract

TlBr is a promising semiconductor for gamma-ray detection at room temperature, but it has to be extremely pure to become useful. We investigated the purification and crystal growth of TlBr to improve the mobility and lifetime of charge carriers, and produce TlBr detectors for radioisotopic detection. Custom equipment was built for purification and crystal growth of TlBr. The zone refining and crystal growth were done in a horizontal configuration. The process parameters were optimized and detector grade material with an electron mobility-lifetime product of up to 3x10 -3 cm 2 /V has been produced. The material analysis and detector characterization results are included.

Towards time-of-flight PET with a semiconductor detector

“…The optical absorption of two TlBr samples with 5 mm and 10 mm thicknesses were measured. The TlBr slabs were manufactured by Radiation Monitoring Devices, Inc., as previously described [Churilov et al . 2008].…”

TlBr and TlBr I1− crystals for γ-ray detectors

“…Both planar devices and small pixel arrays have been fabricated. The planar detectors were mounted to ceramic substrates, and the pixelated arrays were mounted to chip carriers [8].…”

“…Initially, TlBr was not practically interesting because of the poor mobility-lifetime product of charge carriers (mt) e $10 À 6 cm 2 /V [5]. TlBr has gained more attention recently, after several research groups including RMD managed to improve the (mt) of electrons through purification [6][7][8]. This allowed fabrication of larger devices with higher detection efficiency.…”

Temperature dependence of the indirect bandgap in thallium bromide from cathodoluminescence spectroscopy

“…Measurements were made on nominally undoped detector grade materials. 13 The starting material is a 5N purity TlBr compound, which is then zone refined $100 times prior to final THM crystal growth.…”