Mobility-lifetime Product Characterization Of Long CdZnTe Room-temperature Semiconductor Gamma-ray Detectors

Cadmium zinc telluride (Cd1-xZnxTe or CZT), a ternary semiconductor material is well suited and has been the material of choice for good charge collection efficiency and high energy resolution room temperature x- and gamma-ray radiation detectors. In addition, these detectors can be small in size, have fast timing characteristics, and the effective thickness can be varied. CZT detector fabrication, and the characterization and analysis of the mobility-lifetime (µτ) product in long (thick) CTZ detectors was performed in this study using large area CZT detectors. Four 2 cm long CZT detectors were fabricated and pulse height energy spectra collected using a 241Am source of high energy photons. All the long CZT detectors achieved fair energy resolutions from 8 to 11%, at different applied biases, requiring further improvement. Charge Collection Efficiency (CCE), the measured collected charges in the long CZT detectors saturate at higher applied bias. The deposited charges agree well with the expected amount of charge at the higher applied bias, leading to a conclusion that these long CZT detectors do not show measurable electron trapping, and charge collection is feasible in long detectors, but improved energy resolution is required for high energy x- and gamma-ray detection.