Abstract
Herein, the optoelectrical investigation of cadmium zinc telluride (CZT) and indium (In) doped CZT (InCZT) single crystals-based photodetectors have been demonstrated. The grown crystals were configured into photodetector devices and recorded the current-voltage (I-V) and current-time (I-t) characteristics under different illumination intensities. It has been observed that the photocurrent generation mechanism in both photodetector devices is dominantly driven by a photogating effect. The CZT photodetector exhibits stable and reversible device performances to 632 nm light, including a promotable responsivity of 0.38 AW−1, a high photoswitch ratio of 152, specific detectivity of 6.30 × 1011 Jones, and fast switching time (rise time of 210 ms and decay time of 150 ms). When doped with In, the responsivity of device increases to 0.50 AW−1, photoswitch ratio decrease to 10, specific detectivity decrease to 1.80 × 1011 Jones, rise time decrease to 140 ms and decay time increase to 200 ms. Moreover, these devices show a very high external quantum efficiency of 200% for CZT and 250% for InCZT. These results demonstrate that the CZT based crystals have great potential for visible light photodetector applications.
Highlights
Cadmium zinc telluride (CdZnTe or cadmium zinc telluride (CZT)), a p-type semiconductor have recently gained much attention in the key detector technologies
Photodetectors based on lead dihalide (LDH)and transition metal dichalcogenides (TMD) have shown promising results but they suffer from environmental instability due to oxygen chemisorption effect[20,21,22,23,24]
The observed X-ray diffractometer (XRD) peaks in both specimens correspond to the cubic crystal system of space group F-43mE (216) and crystals were grown in the direction of (111) plane, confirmed from standard JCPDS# 50–1438
Summary
The main attractive aspect of CZT crystals are (i) wide band gap (~1.68 eV) which is necessary for room temperature operation, (ii) a large photon absorption cross section (∼104 cm2/g for 1 keV photon energy; for photon energy 95%) for efficient conversion of optical energy in to electrical energy, and (iii) high resistivity (1010 Ω.cm) to minimize the noise due to limiting the leakage current[1,2,3,4,5] These specific properties allow its applications in a wide range of devices such as X-ray or γ-ray detector, nuclear spectroscopy, medical imaging, radiation sensors, photorefractive, etc.[6,7,8,9,10]. We have measured the illumination dependence current-voltage (I-V) and current-time (I-t) curves and calculated the detectivity, responsivity, EQE, photoconductivity and switching time of photodetectors
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