Effects of Defects to the Performance of CdTe Pad Detectors in IBIC Measurements

We studied the impact of boundary walls and inclusions to the charge collection efficiency (CCE) of cadmium telluride (CdTe) pad detectors. By using ion beam-induced charge (IBIC) analysis, we were able to locate and classify various defects. We used 2-MeV protons that have a penetration depth of about 40 $\mu \text{m}$ in bulk CdTe. The detectors we measured had a surface area of 1 cm $\times \,\, 1$ cm and a thickness of 1 mm. They were passivated either by using aluminum nitride (AlN) or by aluminum oxide (Al2O3) and had a mesh of titanium tungsten Schottky contacts on both anode and cathode sides. In this paper, we show the results of our measurements and analyze the potential impact of the found defects on the performance of CdTe detectors with Geant4 simulations.