Surface passivation and contacts in CdZnTe X-rays and gamma-rays detectors

Surface passivation and contact deposition are important processes in the fabrication of cadmium zinc telluride (CdZnTe) X-rays and gamma-rays detectors. Surface passivation is used to reduce the effects of fabrication-induced surface defects. It is also used to reduce defects that could result from aging of the detector. Another important factor in charge collection is the interface between the electrical contacts and the detector wafer. In this paper, we present the results of the effects of chemo-mechanically polishing CdZnTe wafers with a hydrogen bromide in hydrogen peroxide solution followed by passivation in a mixture of potassium hydroxide in hydrogen peroxide solution by monitoring their energy resolutions over a 4-day period. The results showed that the 59.5-keV gamma peak of Am-241 remains under the same channel over the 4 days.