Evaluation of CdTe(Cl) crystal growth with THM and application to a multichannel detector

Abstract

Abstract The relationship between the properties of a CdTe radiation detector and its crystal growth condition has been studied. The crystals were grown from an excess Te solution doped with chlorine using radio frequency (RF-THM) and ordinary travelling heater methods (OR-THM). The concentration of chlorine atoms in the CdTe crystal grown by the RF-THM method is estimated to be about 1017 /cm3 and is the same as the concentration in the crystal grown by the OR-THM method. However, the CdTe detector characteristics show excellent properties in the detector fabricated by the RF-THM technique. The depth profile of Cl dopants has been measured by using the SIMS technique and homogeneity of the Cl distribution in the crystal grown by the RF-THM is recognized. It is suggested that the characteristics of the detector depend strongly on the chlorine distribution. In order to investigate the Cl-related emission bands, edge and bound-exciton emission spectra were measured at 4.2 K by photoluminescence. It is suggested that the 1.554 eV emission band is related to the Cl impurity level and that the characteristics of the radiation detector are affected strongly by the appearance of this level. A 46 channel array detector can be produced using high-resistivity CdTe:Cl crystals grown by the RF-THM technique.