Investigation of the electronic properties of cadmium zinc telluride (CZT)detectors using a nuclear microprobe

The electronic transport properties of Cadmium Zinc Telluride (CZT) determi ne the charge collection efficiency (i.e. the signal quality) of CZT detect ors. These properties vary on both macroscopic and microscopic scales and d epend on the presence of impurities and defects introduced during the cryst al growth. Ion Beam Induced Charge Collection (IBICC) is a proven albeit re latively new method to measure the charge collection efficiency. Using an i on microbeam, the charge collection efficiency can be mapped with submicron resolution, and the map of electronic properties (such as drift length) ca n be calculated from the measurement. A more sophisticated version of IBICC , the Time Resolved IBICC (TRIBICC) allows us to determine the mobility and the lifetime of the charge carriers by recording and analyzing the transie nt waveform of the detector signal. Furthermore, lateral IBICC and TRIBICC can provide information about how the charge collection efficiency depends on the depth where the charge carriers are generated. This allows one to de duce information on the distribution of the electric field and transport pr operties of the charge carriers along the detector axis. IBICC and TRIBICC were used at the Sandia microbeam facility to image electronic properties o f several CZT detectors. From the lateral TRIBICC measurement the electron and hole drift length profiles were calculated. (C) 2001 Elsevier Science B .V. All rights reserved.