Motosada Kiri

Local polarization phenomena in In-doped CdTe X-ray detector arrays

Local polarization phenomena have been studied in detector arrays with the detector element size of 500 /spl mu/m/spl times/500 /spl mu/m, which are fabricated from high-resistivity In-doped CdTe crystals grown by the vertical Bridgman technique. It has been found for the first time that a polarization effect, which is characterized by a progressive decrease of the pulse counting rate with increasing photon fluence, strongly depends on the detector elements, that is, the portion of crystals used. The influence of several parameters, such as the applied electric field strength, time, and temperature, on this local polarization effect is also investigated. From the photoluminescence measurements of the inhomogeneity of In dopant, it is concluded that the local polarization effect observed here originates from an deep level associated with In dopant in CdTe crystals. >