Evaluation of CdTe detectors with Schottky contacts for imaging applications

A CdTe detector with Schottky contacts has been tested with special emphasis on the requirements for imaging arrays. The detector can withstand a much higher field strength than conventional CdTe detectors with two ohmic contacts. The higher field strength results in complete charge collection, including the holes which are a factor of 10 slower than the electrons. With moderate cooling to −20°C and a field strength around 10 kV/cm, the detectors are homogeneous, i.e. the signal response is independent of the interaction location of the γ-rays. The measured spectra show symmetric full energy peaks with no tailing to the low-energy side. Polarization effects at room temperature disappear below 0°C. The detectors are well suited for large imaging arrays in applications such as hard X-ray astrophysics and medical imaging.