CZT detectors are fabricated with very thin metalized electrode geometries deposited on the detector surfaces. These electrodes are then electrically biased creating a difference in electrical potential within the detector volume. When ionizing radiation interacts with the CZT crystal, a large number of pairs of electrons and holes are created in proportion to the energy of the incoming radiation.
The negatively charged electrons and positively charged holes then migrate to the oppositely charged electrodes where they are collected. The resulting charge pulse is then detected by the preamplifier, which produces a voltage pulse whose height is proportional to the incident energy of the incoming photon. The signal from the preamplifier is then fed into a shaping amplifier that converts the signal into a Gaussian pulse and amplifies it. The signal can then be fed into a standard counting system or Multi-Channel Analyzer (MCA) to generate the characteristic spectrum for the incoming photons. We usually couple the cadmium zinc telluride CZT-based detector to an ASIC (application specific integrated circuit) to reduce the size and cost of the readout electronics.