A novel surface passivation process for CdZnTe detector packaging

The CdZnTe (CZT) micro-strip detector packaging plays a dominant role in detector performance, which can decrease the noise of the detectors and improve the spectral energy resolution. The surface passivation of CdZnTe detectors is an important step in the device packaging. In this paper, comparison between chemical and physical passivation processes has been made. In particular, a new surface passivation process for CZT has been studied by depositing diamond like carbon (DLC) film with radio frequency plasma chemical vapor deposition (RFPCVD) method. The micro-structural, chemical and electric characteristics of the passivation layers were identified by AFM, AES and micro Raman spectroscopy and ZC36 micro-current testing instrument. The results show that the DLC on the detector has the characteristic diamond peak of the sp³ structure and can prevent the outward diffusions of Cd or Te components from the CZT surface. The inter-strip resistance in a coplanar grid detector by the DLC passivation is about 12GQ with inter-strip distance 25 μrn. Therefore, it could be inferred that DLC seems a more likely candidate for maintaining high long-term performance, especially for technology facilitation of the fabrication of micro-strip detectors.