Enhanced UV detection performance of a CdZnTe-based photodetector through surface polishing treatments

Abstract

The reduction in the surface states of cadmium zinc telluride (CZT) films is essential to fulfill the requirements for UV detection. However, the implementation of a CZT-based UV detector has encountered a major issue of large leakage current that arises from the surface roughness and surface defects formed during the material growth. In this work, a combination of surface treatments involving mechanical polishing (MP) + chemical-etching polishing (CP) + passivation is proposed to circumvent this issue to enhance the performance of a CZT-based UV detector. The surface roughness of the as-grown CZT film exceeds the measurement limitations of atomic force microscopy, while the root mean square (RMS) of the roughness of the CZT films after surface combination treatment is reduced to as low as 2.3 nm. The CZT-based UV detector after being MP + CP + NH₄F/H₂O₂ treated exhibits excellent UV photoresponse performance of a high photocurrent-to-dark current ratio (PDCR) of ∼100, a rise time of 210 ms and a decay time of 400 ms under 365 nm UV illumination at 1 V bias. The PDCR, rise time and decay time of the as-treated detector are 25 times greater, and 3.7 and 2.7 times faster than those of the as-grown CZT-based detector, respectively. The present work offers a promising strategy to develop the CZT-based UV detector that has good detection performance of a high PDCR, and short rise and decay times.