Time-of-Flight Measurements on Schottky CdTe Detectors

The internal electric field distribution of Schottky barrier CdTe detectors was evaluated by using time-of-flight (TOF) measurements combined with Monte Carlo (MC) simulation. The evolution of the current waveforms from less than 1 s up to about 1300 s of DC bias duration was measured at room temperature. The observed temporal behavior of the current waveforms was well reproduced by MC simulation with simple linear variation of the electric field strength distribution with position x from the anode electrode. These observations indicate accumulation of negative space charges, which screens the applied electric field progressively from the cathode side toward the bulk. Based on the evolution of the current waveforms we can successfully extract the temporal evolution of electric field distribution characterized by triple exponential function.