Performance optimization of CZT thick films by CdTe buffer layers for solar-blind ultraviolet photoelectric detectors

CdZnTe (CZT) thick films with CdTe buffer layers (CZT/CdTe) were studied for high-performance ultraviolet photoelectric detector. CZT thick films were prepared on AlN/Si substrates via close-spaced sublimation (CSS) and CdTe buffer layers were introduced to optimize the interface quality of CZT thick films. Results of x-ray diffraction showed that the full width at half maximum (FWHM) and dislocation density (delta) of interface of optimized samples were 0.156 degrees and 2.543 x 1014 lin/m2, respectively. Interface detect analysis of free-standing CZT and CZT/CdTe thick films was studied by x-ray photoelectron spectroscopy (XPS) and low-temperature photoluminescence (PL) spectroscopy, and mechanism of in-situ annealing in CdTe atmosphere to reduce interfacial defect states was discussed. Moreover, the photo-dark current ratio of the CZT/CdTe thick film metal-semiconductor-metal (MSM) structural photodetector was as high as 5530, which was nearly double that of the CZT thick film detector, and the carrier mobility lifetime product could reach 5.59 x 10-4 cm2/V at 100 V bias, confirming the improvement of carrier transport capacity and detection efficiency. CZT-based detectors have inestimable prospect in the field of solar-blind ultraviolet detection with the participation of CdTe buffer layers.