Charge carrier transport properties in thallium bromide crystals used as radiation detectors

The authors report on measurements of the two most important transport parameters, the mobility mu and the mean trapping time tau for electrons and holes, in TlBr crystals prepared in the laboratory. The results using the transient charge technique are presented along with the data obtained by the pulse height spectrum analysis. The values of ( mu tau )/sub e/ and ( mu tau )/sub h/ measured for TlBr are still lower than those reported for more established detector materials such as CdTe and HgI/sub 2/. It is noted, however, that purer TlBr exhibited somewhat improved transport characteristics, implying that mu tau may still be impurity-limited. For this reason, future improvements in purification will probably yield detectors having improved charge carrier transport.>