Investigation of degradation of electrical and photoelectrical properties in TlBr crystals

AbstractTheinterestinTlBrasadetectormaterialisduetoitshighaverageatomicnumber,highdensityandwidebandgap.The photon stopping power of TlBr crystals is greater than that of any of the semiconductors considered today,therefore this material is promising for X- and g-ray detector applications. However, the observed stability of TlBrradiationdetectorsisnotgoodandthereforetheinvestigationofdegradationphenomenaandimprovingthepropertiesareimportantforthefutureofdetectors.Theresultsofinvestigationofelectricalproperties,photoconductivityandtheirdegradationwereinvestigatedinTlBrsinglecrystals.Itisproposedthationicconductivitycreatesamicroinhomogeneityofthesamplesandthisprocessisactivatedbyelectricfieldandbynonequilibriumcarriergeneration.Theobservedthresholdtypeeffectsarerelatedtothegrowthofstructuraldefects.r 2004ElsevierB.V.Allrightsreserved. Keywords: TlBr;Ionizingradiationdetectors;Polarizationphenomena;Degradation 1. IntroductionDuringrecentyearsithasbecomeapparentthatthallium bromide is a promising material forionizing radiation detectors. The interest in TlBrisdue toits highaverage atomic number(Tl: 81,Br:35),highdensity(7.5g/cm