Investigation of response behavior in CdTe detectors versus inter-electrode charge formation position

Some important features of semiconductor detectors (pulse height, energy re solution, photopeak efficiency) are strongly affected by charge collection efficiency; therefore low charge mobility and trapping/detrapping phenomena can more or less degrade the CdTe based detectors performance, depending o n the distance between the charge formation location and the collecting ele ctrodes. Using a narrow photon beam, obtained by a 20 mm thick tungsten collimator, we have studied the response of a small sample of CdTe(Cl) planar detectors . In particular we have investigated the behavior of the above parameters v s. the charge formation position induced by the incoming radiation irradiat ing the detectors perpendicularly to the electric field and performing a fi ne scanning of the inter-electrode region [1]. For comparison the detectors were irradiated also with a non collimated bea m both perpendicularly and in the classical configuration (through the cath ode).