Effect of surface treatment on photo-electric properties of CZT thick film for radiation detector

The rough surface of CZT film is detrimental to both the surface leakage current and photoelectric response sensitivity. Here, the effect of different surface treatment techniques, such as manual mechanical polishing, chemical etching and passivation, on surface quality and photoelectric properties of the CZT thick film was investigated. The results demonstrated that a combination of surface treatments including mechanical polishing, chemical etching, and passivation can effectively improve the surface quality of CZT polycrystalline thick film, thus reducing the surface leakage current. The dark current of MPEP treated by mechanical polishing, chemical etching and passivation in turn is one order of magnitude smaller than that of as-grown CZT film. The resistivity of MPEP is 1.20 × 1010 Ω cm, which is 8.1 times that of as-grown film. The combination of surface treatment process greatly reduced surface leakage current, improved the resistivity and X-ray photoconductivity response performance of CZT coplanar detector. Our findings provide a guide for surface treatment to further improve both the photoelectric properties of photodevice based on the CZT thick film.