Enhancing photoresponse time of low cost Pd/ZnO nanorods prepared by thermal evaporation techniques for UV detection (original) (raw)

Theoretical and Experimental Study of UV Detection Characteristics of Pd/ZnO Nanorod Schottky Diodes

Nano, 2017

In this work, we report theoretical and experimental study of Pd/ZnO nanorod (NR) Schottky diodes-based ultraviolet photodetector (UV-PD). The ZnO-NRs are deposited on indium tin oxide (ITO) coated glass substrates by using a low-temperature hydrothermal method. The surface morphology of the ZnO-NRs film is characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The SEM image shows vertically grown NRs with uniformity, and XRD shows the preferred (002) orientation of ZnO-NR films. The current–voltage characteristics of Pd/ZnO-NR Schottky diodes are studied under dark and UV light. A voltage bias from [Formula: see text]1[Formula: see text]V to [Formula: see text]1[Formula: see text]V is applied and the ratio of photocurrent to dark current was ([Formula: see text] at [Formula: see text][Formula: see text]V) calculated from the [Formula: see text]–[Formula: see text] curve. The value of responsivity was found to be 0.111[Formula: see text]A/W at [Formula: see...

Design and analysis of UV detector using ZnO nanorods on interdigitated electrodes

2016

ZnO nanorods are widely used as UV detectors. Sensitivity of the UV detectors can be increased by growing the nanorods on an array of interdigitated electrodes. This paper reports a relationship between sensitivity of the UV sensor i.e. the ZnO nanorods and efficiency of the interdigitated electrodes over which the rods are grown. Keywords:UV sensor, ZnO nanorods, interdigitated electrodes

Interface architecture determined the performance of ZnO nanorods-based photodetectors

Chemical Physics Letters, 2014

High density ZnO nanorods grown on silicon oxide-coated Si (1 1 1) substrates were used to fabricate an MSM UV photodetector. The maximum sensitivity of the detector was about 1150, which was maintained over the wide range of applied bias. The photodetector responsivity increased slightly until reaching a maximum value at 374 nm and exhibited a sharp cutoff at 378 nm. The obtained photodetector responsivity was as high as 1.1 A/W. The detector shows fast photoresponse with a rise time of 0.008 s and a decay time of 0.021 s.

A study of hydrothermally grown ZnO nanorod-based metal-semiconductor-metal UV detectors on glass substrates

Nanomaterials and Nanotechnology

This study reports hydrothermally grown zinc oxide nanorod-based metal-semiconductor-metal ultraviolet detectors with palladium metal as the electrodes. The zinc oxide nanorods were deposited on glass substrates in two steps, seed layer deposition and growth of nanorods. The structural and optical properties of nanorods were examined using scanning electron microscopy and ultraviolet–vis spectroscopy, respectively. The scanning electron microscopy image showed that the growth of nanorods was uniform, and the ultraviolet–vis results indicate that the bandgap of zinc oxide nanorods was 3.23 eV. For metal-semiconductor-metal devices, interdigited metal electrodes with equal interelectrode spacing and a width of 0.3 mm were deposited above the zinc oxide nanorod thin films with a shadow mask using a thermal evaporation system. The current–voltage characteristics of the metal-semiconductor-metal detector were investigated and it showed a contrast ratio of approximately 2.10 and responsiv...

Low power UV photodetection characteristics of cross-linked ZnO nanorods/nanotetrapods grown on silicon chip

High-quality cross-linked ZnO nanorods/nanotetrapods have been successfully synthesized via thermal evaporation of Zn metal grains on Si (1 0 0) substrates. The growth mechanism for the formation of such cross-linked ZnO nanorods is discussed. The morphological, structural and optical properties of the nanorods have been investigated using scanning electron microscopy, X-ray diffraction, Raman spectroscopy and photoluminescence techniques. Cross-linked ZnO nanorods-based metalsemiconductor-metal UV detectors (Ag-ZnONRs-Ag MSM PD) were fabricated. The device showed a sensitivity of 595. The responsivity (R) of the device is 0.63 A W −1 , which is 10 times higher than that reported for ZnO-based PDs. Under low power illumination (365 nm, 1.5 mW/cm 2 ), the device showed a relatively fast response and baseline recovery for UV detection. The prototype device shows a simple method for cross-linked nanorods synthesis and demonstrates the possibility of constructing nanoscale photodetectors for nano-optics applications.

Electrical and optical effects of Pd microplates embedded in ZnO thin film based MSM UV photodetectors: A comparative study

Sensors and Actuators A-physical, 2014

This paper reports the characterization of ZnO-based interdigitated metal-semiconductor-metal (MSM) Schottky barrier UV photodetectors fabricated by three methods. Specifically, devices having Pd Schottky contacts based on un-doped ZnO, Pd doped ZnO and Pd microplates embedded ZnO films. All ZnO films were grown on p-type Si 1 1 1 substrates by the sol-gel method. For embedded devices, Pd microplates where first grown on the substrate by thermal evaporation using a 80 m mesh shadow mask. We have estimated the photocurrent, contrast ratio, responsivity, and quantum efficiency of the photodetectors for applied voltage from −5 to 5 V and optical power from 50 to 200 W at 365 nm. The current-voltage characteristics were studied and parameters such as ideality factor, leakage current, and barrier height of the Schottky contacts were extracted. The barrier height dependence on the electric field and tunneling through the barrier has been taken into account of the studied MSM devices. The bandgap of both undoped ZnO and ZnO:Pd are evaluated from the absorbance spectra via double beam spectrophotometry. Surface morphology of the ZnO films was studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM). All devices showed a maximum photo-response at flat band voltages of MSMs. It was found that there is no significant difference between un-doped and Pd doped ZnO derived devices performance. The study also revealed that the Pd microplates embedded ZnO films resulted in devices exhibiting better photoresponse as compared to those using un-doped ZnO and ZnO:Pd thin films.

High-responsivity self-powered UV photodetector performance of pristine and V-doped ZnO nano-flowers

Optics and Laser Technology, 2023

Wurtzite ZnO nanostructures are suitable for high-performance, self-powered photodetectors (PDs) because of their attractive optoelectronic properties. In this study, highly sensitive ultraviolet self-powered PDs with high responsivity/detectivity and large external quantum efficiency was developed by V-doped ZnO nanoflower samples onto an ITO glass substrate. Highly faceted pristine and V-doped ZnO nanoflowers were produced using a simple, low-cost co-precipitation method. The presence of Na + ions in the precursor solution appeared to control the morphology of the nanomaterial. Various physicochemical characterizations showed that the variation of the Na + ion concentration inhibits the reaction at selected regions, causing the branching of nanostructures to form ZnO nanoflowers. Room-and low-temperature photoluminescence studies showed that Vdoping increases the extrinsic carrier density and produces many intrinsic and extrinsic defect states, which reduce the e −-h + recombination rate significantly and produce a large photocurrent under UV illumination. The V-ZnO-based self-powered UV PD device showed a 156 % increase in photocurrent compared to pristine ZnObased PDs, with very short response/recovery times of 0.22/0.23 s under 382 nm UV illumination of 1.14 mW/cm 2 , and excellent responsivity (5.1 × 10 3 mA/W), very high external quantum efficiency (5.5 × 10 4 %), and large detectivity (4.0 × 10 13 Jones). Therefore, the current work presents a simple way to obtain highperformance self-powered UV PDs that can open up a new horizon to fabricate new-generation optoelectronic devices for diverse applications.

Characterization of ZnO metal–semiconductor–metal ultraviolet photodiodes with palladium contact electrodes

Semiconductor Science and Technology, 2007

ZnO metal-semiconductor-metal (MSM) photodiodes with palladium (Pd) contact electrodes were fabricated. It was found that the barrier height at the Pd/ZnO interface was 0.701 eV. With an incident wavelength of 370 nm and 1 V applied bias, it was found that the maximum responsivity of the Pd/ZnO/Pd MSM photodiodes was 0.051 A/W, which corresponds to a quantum efficiency of 11.4%. For a given bandwidth of 100 Hz and 1 V applied bias, we found that the noise equivalent power and the corresponding detectivity D * were 1.13 × 10 −12 W and 6.25 × 10 11 cmHz 0.5 W −1 , respectively.