ZnO Ultraviolet Photodetectors Research Articles

Ferroelectric Tuning of ZnO Ultraviolet Photodetectors.

The ferroelectric field effect transistor (Fe-FET) is considered to be one of the most important low-power and high-performance devices. It is promising to combine a ferroelectric field effect with a photodetector to improve the photodetection performance. This study proposes a strategy for ZnO ultraviolet (UV) photodetectors regulated by a ferroelectric gate. The ZnO nanowire (NW) UV photodetector was tuned by a 2D CuInP2S6 (CIPS) ferroelectric gate, which decreased the dark current and enhanced the responsivity and detectivity to 2.40 × 104 A/W and 7.17 × 1011 Jones, respectively. This strategy was also applied to a ZnO film UV photodetector that was tuned by a P(VDF-TrFE) ferroelectric gate. Lower power consumption and higher performance can be enabled by ferroelectric tuning of ZnO ultraviolet photodetectors, providing new inspiration for the fabrication of high-performance photodetectors.

Paper-based ZnO ultraviolet photodetector with enhanced stability and detectivity by PTFE coatings

Paper-based ZnO ultraviolet photodetector with enhanced stability and detectivity by PTFE coatings

Improved Optoelectronic Characteristics of Ga-In co-Doped ZnO UV Photodetectors by Asymmetric Metal Contact Structure

Transparent Ga and In co-doped ZnO (ZnO:Ga-In) semiconductor thin films were deposited on Corning glass substrates by the sol-gel spin-coating process. The ZnO:Ga-In thin films were used as the sensing layer of metal–semiconductor–metal (MSM)-type ultraviolet (UV) photodetectors (PDs). In this study, the optoelectronic characteristics of ZnO:Ga-In MSM PDs with symmetrical interdigital electrodes (Al–Al) and asymmetrical interdigital electrodes (Al–Au) were compared. The as-prepared ZnO:Ga-In thin films were polycrystalline, and they had a single-phase hexagonal wurtzite structure and high transparency (~88.4%) in the visible region. The MSM-PDs with asymmetric electrodes had significantly reduced dark current (9.6 × 10−5 A at 5 V) according to the current-voltage (I-V) characteristics and higher photoresponse properties than those of the MSM-PDs with symmetric electrodes, according to the current-time (I-t) characteristics. In addition, the Al–Au devices were self-powered without an applied bias voltage. The photocurrent was 6.0 × 10−5 A; the sensitivity and responsivity were 0.25 and 0.03 mA/W, respectively, under UV illumination.

Chemo-phototronic effect induced electricity for enhanced self-powered photodetector system based on ZnO nanowires

Self-powered ultraviolet (UV) photodetectors based on ZnO nanowires have attracted considerable interest due to low-cost and ease of fabrication. Effective strategies to enhance their photoresponse still remain challenging. Here we report a 4 × 4 matrix of self-powered ZnO UV photodetector system with optimized ZnO nanowire photoelectrode/electrolyte heterostructures. Modulating pH-dependent chemo-phototronic effect can regulate optoelectric and chemoelectric processes, resulting in significantly improved photodetection performance. The maximum photocurrent and photoresponsivity up to 290.02 μA and 4.74 × 10−2 A W−1 can be achieved by using NaOH aqueous electrolyte (pH 13), which have been enhanced by 2056% as compared with that of utilizing deionized water electrolyte (pH 7). The enhanced performance is related to the pH-dependent chemical reaction, Schottky-like barrier height and depletion region width modulation at ZnO/electrolyte interface. This work provides guidelines to fabricate high-performance self-powered photodetector system of using semiconductor/electrolyte heterostructures, pushing forward the advancement of high-sensitivity and low-cost photodetector array system.

Use of Organic Polymer P3HT:PC61BM as the Active Layer to Improve the Performance of ZnO Ultraviolet Photodetector

Use of Organic Polymer P3HT:PC61BM as the Active Layer to Improve the Performance of ZnO Ultraviolet Photodetector

Performance Enhancement of a ZnO-based UV Photodetector Using Patterned Ag Nanoparticles

We studied the effect of a localized surface plasma resonance (LSPR) on ZnO-based ultraviolet photodetectors (UV-PDs) with periodic patterns of Ag nanoparticles (NPs), which had been formed by wrong a nanosphere lithography technique with a mask of polystyrene nanosphere arrays. The periodically patterned Ag NPs were positioned at the interface between the ZnO channel layer and the Si substrates, and the PD structures were constructed by forming two Al electrodes on the surface of the ZnO layer. Under λ = 365 nm UV light corresponding to the bandgap of ZnO, the photocurrent and the photoresponsivity of the ZnO UV-PDs with 100-nm-thick Ag NPs were about two times greater than those of PDs without NPs. The maximum responsivity was approximately 0.13 A/W near the 420- nm wavelength, which showed the maximum scattering efficiency. This enhanced performance of the ZnO-based UV-PDs resulting from an increase in the light absorption due to the LSPR of patterned Ag NPs.

电压调制ZnO紫外探测器光响应截止波长的研究

电压调制ZnO紫外探测器光响应截止波长的研究

ZnO ultraviolet photodetectors with an extremely high detectivity and short response time

ZnO thin films have been prepared by atomic layer deposition for ultraviolet photodetection with metal-semiconductor-metal (MSM) structure. The innovation of rapid thermal annealing treatment can modulate the carrier concentration of the ZnO thin films, a lowest carrier concentration of 4.4 × 1014 cm−3 was obtained after annealing at 450 °C, resulting in the minimum dark current of 4.5 × 10−8 A at 5 V. Furthermore, these photodetectors demonstrated respectable responsivity of up to 27 A/W, and the detectivity was enhanced to a fairly high value of 8.5 × 1013 Hz1/2/W together with an extremely rapid response of <80 μs. These performance metrics are far superior compared with the records in the existing literature based on ZnO thin films, and are even on a par with nano-structural ZnO devices, while remain the key features of thin film devices, including high reproducibility and facile preparation.

ZnO ultraviolet photodetector based on flexible polyester fibre substrates by low‐temperature hydrothermal approach

The development of flexible photodetectors is believed to have great potential for future optoelectronic applications, such as biomedical imaging and smart wearable systems. Here the work proposes a simple and low-cost approach for integrating a flexible and wearable ZnO ultraviolet (UV) photodetector using polyester fabric as the platform for the first time. The ZnO nanowires coated polyester fabric was prepared by a low-temperature hydrothermal approach. They measured the performance of the photodetector in terms of I-V characteristics and time-resolved photocurrent. The results showed that the as-fabricated ZnO UV photodetector presented great reliability. Additionally, the working mechanism of the device was also discussed.

The mechanism of photocurrent enhancement of ZnO ultraviolet photodetector by reduced graphene oxide

An ultraviolet (UV) photodetector based on ZnO-reduced graphene oxide (ZnO-rGO) composites have been successfully fabricated. A pure ZnO photodetector was also fabricated by similar method. In comparison with the pure ZnO UV photodetector, the ZnO-rGO photodetector exhibits a much larger photocurrent and a better light-to-dark-current-ratio. The mechanism of photocurrent enhancement was investigated using I-V characteristics, photoluminescence (PL) spectra, transmittance spectra and time-dependent photocurrent analysis. Results show that the photocurrent enhancement of the ultraviolet photodetector is due to the improvement of the carrier lifetime, because the carrier recombination of ZnO were reduced by rGO. It provides a potential way to fabricate high-response UV photodetectors.

ZnO Ultraviolet Photodetector Modified with Graphdiyne

ZnO Ultraviolet Photodetector Modified with Graphdiyne

A ZnO-Based Programmable UV Detection Integrated Circuit Unit

We have fabricated a programmable ultraviolet (UV) detection integrated circuit unit consisting of a ZnO thin film transistor (TFT) and a ZnO thin film UV photodetector (PD). The prepared ZnO-TFT shows good switching characteristics with an ON/OFF ratio of more than $10^{4}$ . The ZnO UV PD has outstanding UV photocurrent characteristics, with a light-to-dark-current ratio more than $10^{4}$ under 365 nm UV light of 1.224 mW/cm2. It also shows a stable, reproducible, and rapid response with a rise time of 35.0 ms and a fall time of 43.9 ms when exposing to periodically switched UV light illumination. ZnO-TFT and ZnO thin film UV PD were integrated into a resistance load circuit unit. The results show that the output current in the circuit is only observed when the ZnO-TFT is turned ON. The current intensity is proportional to the UV intensity. The proposed ZnO-based UV detection integrated circuit unit is able to achieve programmable measurement of UV illumination and supply a new method to obtain all ZnO-based integrated circuit programmable UV detection system.

Controlled enhancement range of the responsivity in ZnO ultraviolet photodetectors by Pt nanoparticles

We report on metal-semiconductor-metal ultraviolet photodetectors based on a ZnO film/Pt nanoparticles/ZnO film composite structure. The responsivity of the sandwich photodetector is 45 times greater for the back-illuminated than the front-illuminated. Surprisingly, the responsivity of a ZnO photodetector without the Pt nanoparticles has rather feeble enhancement under the same conditions (illumination from back and front). The responsivity of the sandwich photodetector can be enhanced from 14 to 45 times by adjusting the embedded depth of the Pt nanoparticles. Combining this result with the optical absorption spectra of ZnO films with and without Pt nanoparticles, we can reasonable to deduce the underlying mechanism and attribute it to the coupling of the localized surface plasmon from Pt nanoparticles with ZnO films. These results demonstrate a method to control the responsivity enhancement by adjusting the embedded depth of the Pt nanoparticles in the sandwich photodetector.

电化学沉积法制备ZnO纳米柱及自驱动紫外探测性能研究

电化学沉积法制备ZnO纳米柱及自驱动紫外探测性能研究

High spectrum selectivity and enhanced responsivity of a ZnO ultraviolet photodetector realized by the addition of ZnO nanoparticles layer.

A photodetector with a high spectrum selectivity and enhanced responsivity has been realized in the ZnO NPs coated Au/ZnO/Au structure. In this structure, the ZnO NPs act as the "filter" that filtrates out the short-wavelength photons to ensure the high spectrum selectivity of the photodetector, whereas on the other hand they act as the "scatterer" to scatter incident light in order to increase the absorption of the ZnO film and consequently enhance the responsivity of the photodetector. In this way, a photodetector with a response width of only 10 nm has been obtained, and the responsivity of the photodetector is 0.052 A W(-1) at 3 V at the wavelength of 376 nm, which is higher than that of the bare Au/ZnO/Au structured photodetector (0.028 A W(-1)). The results reported in this paper may provide a facile route to a highly spectrum-selective photodetector without performance degradation.

Strain-modulation and service behavior of Au–MgO–ZnO ultraviolet photodetector by piezo-phototronic effect

Au–MgO–ZnO (AMZ) ultraviolet (UV) photodetectors were fabricated to enhance their sensitivities by an inserting ultrathin insulating MgO layer. With the insulating layer, the sensitivities of the UV photodetectors were improved via the reduction of the dark current. Furthermore, strain modulation was used to enhance the sensitivities of the AMZ UV photodetectors. The sensitivities of the photodetectors were enhanced by the piezo-phototronic effect. However, there was a limiting value of the applied strains to enhance the sensitivity of the photodetector. When the external strains exceeded the limiting value, the sensitivity decreased because of the tunneling dark current. The external strains loaded on the photodetectors result in the degradation of the photodetectors, and an applied bias can accelerate the process. This work presents a prospective approach to engineer the performance of a UV photodetector. In addition, the study on the service behavior of the photodetectors may offer a strain range and theoretical support for safely using and studying metal–insulator–semiconductor (MIS) UV photodetectors.

Bias induced cutoff redshift of photocurrent in ZnO ultraviolet photodetectors

A ZnO film with a c-axis preferred orientation was prepared on quartz using the radio frequency (RF) magnetron sputtering technique. Then, a metal-semiconductor-metal (MSM)-structured ultraviolet (UV) photodetector was fabricated on the film. It was found that the cutoff wavelength of the photocurrent redshifted from 361 to 379nm when the bias increased from 5 to 30V. The origin of the redshift has been interpreted in terms of a qualitative model considering the declining band gap caused by the bias. This method opens up the possibility of tuning the cutoff redshift of ZnO UV photodetectors.

Oxidized Nano‐Porous‐Silicon Buffer Layers for Suppressing the Visible Photoresponsivity of ZnO Ultraviolet Photodetectors on Si Substrates

This paper demonstrated the fabrication and optoelectronic characteristics of ZnO ultraviolet (UV) photodetectors fabricated on Si substrates with oxidized nano‐porous‐Si (ONPS) buffer layers. ONPS layers were prepared on the surfaces of Si substrates by use of an electrochemical anodization technique following a rapid‐thermal‐oxidation process. Experimental results indicated that application of ONPS buffer layers not only improved the crystallinty of the deposited ZnO thin films but also greatly restricted the visible‐to‐infrared photoresponse that was generated from the light absorption of Si substrates. The developed ZnO‐on‐ONPS photodiodes achieved high photoresponsivity for the incident UV light of 300 ∼ 400 nm and got a large photo‐to‐dark current ratio up to 104 at wavelength of 375 nm under a bias of 5 V. Therefore, ZnO on ONPS provides a highly potential approach for the development of low‐cost visible‐blind UV photodetectors.

Reliable self-powered highly spectrum-selective ZnO ultraviolet photodetectors

Ultraviolet photodetectors (PDs) have been fabricated from p-ZnO:(Li,N)/n-ZnO structures in this Letter. The PDs can operate without any external power supply and show response only to a very narrow spectrum range. The self-power character of the devices is due to the built-in electric field in the p-n junctions that can separate the photogenerated electrons and holes while the high spectrum-selectivity has been attributed to the filter effect of the neutral region in the ZnO:(Li,N) layer. The performance of the self-powered highly spectrum-selective PDs degrades little after five months, indicating their good reliability.

Low-Frequency Noise Characteristics of In-Doped ZnO Ultraviolet Photodetectors

We report the growth of vertically aligned indium-doped ZnO (IZO) nanorods on a glass substrate using a low-temperature hydrothermal method. An IZO nanorod metal-semiconductor-metal (MSM) ultraviolet (UV) photodetector (PD) was also fabricated. It was found that the UV-to-visible rejection ratio of the fabricated PD was ~109 when biased at 1 V with a sharp cutoff at 390 nm. With an incident light wavelength of 390 nm and an applied bias of 1 V, it was found that measured responsivity of the PD was 2.5 A/W. Furthermore, it was also found that the noise equivalent power and detectivity of the fabricated IZO nanorod MSM PD were 1.42×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> W and 1.44×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm·Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sup> ·W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , respectively.