Effect of passivation sequence on the performance of planar CdZnTe detectors

Passivation is usually used to reduce the leakage current between contacts of CdZnTe devices with pixel electrodes. For CdZnTe devices with planar electrodes, different passivation sequences and passivation regions result in two different device structures. In this paper, two different passivation sequences were used to treat the etched CdZnTe: depositing electrodes followed by passivation, and passivation followed by depositing electrodes, the difference they caused was whether the region below the contact was passivated. The leakage currents of the two structures were compared, and chemical components and Schottky barriers produced by these two different treatments were measured and discussed. Finally, the energy spectra of the two treatments were tested. It was found that, for CZT devices with planar electrodes, the method of depositing electrodes after passivation could significantly reduce the leakage current, although the contacts and CZT were separated by the passivation layer, however, the lower noise from reduced leakage current improved the energy resolution.