Noise in CdZnTe detectors

• Published in: IEEE transactions on nuclear science Vol. 48; no. 3; pp. 282 - 286
• Main Authors: Luke, P.N., Amman, M., Lee, J.S., Manfredi, P.F.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-06-2001; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Cadmium zinc tellurides; Carriers; Current measurement; Detectors; Devices; Electrodes; Leak detection; Leakage current; Noise; Noise generators; Noise level; Noise measurement; Noise reduction; Shot noise; White noise
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/23.940066

Noise in CdZnTe devices with different electrode configurations was investigated. Measurements on devices with guard-ring electrode structures showed that surface leakage current does not produce any significant noise. The parallel white noise component of the devices appeared to be generated by the bulk current alone, even though the surface current was substantially higher. This implies that reducing the surface leakage current of a CdZnTe detector may not necessarily result in a significant improvement in noise performance. The noise generated by the bulk current is also observed to be below full shot noise. This partial suppression of shot noise may be the result of Coulomb interaction between carriers or carrier trapping. Devices with coplanar strip electrodes were observed to produce a 1/f noise term at the preamplifier output. Higher levels of this 1/f noise were observed with decreasing gap widths between electrodes. The level of this 1/f noise appeared to be independent of bias voltage and leakage current but was substantially reduced after certain surface treatments.