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Fast Response of UV Photodetector Based on Ag Nanoparticles Embedded Uniform TiO2 Nanotubes Array
摘要： Titanium dioxide (TiO2) has drawn a potential research interest for ultraviolent (UV) photodetector (PD) applications because of its tunable bandgap in UV absorption region, low-absorption coefficient in visible region, n-type semiconducting property, and excellent chemical stabilities. In this study, attempts were made to explore the performances of TiO2 nanostructures such as nanotubes (NTs) and nanorods (NRs) based UV PDs embedded with 23 nm plasmonic silver (Ag) nanoparticles (NPs), which offer the local surface plasmonic resonance or near-field enhancement. The vertical TiO2 NTs and NRs with high uniformity and height of 1 μm were successfully synthesized using simple and low-cost electrochemical anodization and hydrothermal growth techniques, respectively onto Ti substrates. From the x-ray diffraction analysis, it was ascertained that the anatase phase has been formed for NTs, whereas the rutile phase dominated the NRs. All these nanostructures were characterized by various material characterization techniques such as field emission scanning electron microscopy, x-ray photoelectron spectroscopy, UV-vis-NIR and Raman spectroscopy to investigate their surface and structural morphologies and absorption spectra. Efforts were put to fabricate Ag/ (with or without Ag NPs) TiO2 nanostructures/ Ti based UV PDs, where Ag has been utilized as top electrode and Ti served the purpose for bottom electrode. The electrical characteristics such as current-voltage, responsivity, detectivity, external quantum efficiency, rise and decay times were systematically investigated under 365 nm UV light illumination. The TiO2 NTs anchored with the Ag NPs offer better photocurrent, responsivity (1.37 AW-1), detectivity (5.18 x 1010 Jones), external quantum efficiency (465.42%), rise (0.43 s) and decay (0.70 s) times. In order to have better insight on the device operational principle, a band diagram was proposed and it was realized that desorption of oxygen ions, increment of free electron carriers, and localized surface plasmonic effect were responsible for obtaining improved photoresponse.
关键词： nanoparticles,UV photodetector,responsivity
更新于2025-09-12 10:27:22
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Plasmonic Nanocavities for High-Responsivity and Broadband Terahertz Detection
摘要： We present a high-responsivity and broadband photoconductive terahertz detector based on a plasmonic nanocavity, which enables high quantum efficiency and ultrafast operation without using short-carrier-lifetime substrates. We experimentally demonstrate that a time-domain spectroscopy setup employing the presented detector can offer 102 dB dynamic range over 0.1-4.5 THz.
关键词： high-responsivity,photoconductive detector,plasmonic nanocavity,broadband,terahertz
更新于2025-09-12 10:27:22
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Design and implementation of LED-LED indoor visible light communication system
摘要： This paper investigates the experimental performance of LEDs as both photo-emitter and photoreceiver. In this work LED-LED link is established using BJT and MOSFET based drive circuits at transmitting side and resistor driver operated in photo-conductive mode is used at the receiver side. The LED response as transmitter and receiver is investigated at different operating frequencies with the distance of up to 20 cm and the data rate of 1 Mbps. The SNR values of 8 dB and 11 dB are obtained using BJT and MOSFET drivers respectively at a distance of 20 cm. Furthermore, six different color LEDs are tested on both sides of transceiver to determine the best performing pair. It is observed that the red color LEDs have good responses as a photodiode due to its long wavelength in the visible spectrum. However their performance is significantly effected by ambient noise. Moreover, the responsivity of the Red color LED operated as photoreceiver with respect to different biasing voltages is also experimentally measured and discussed.
关键词： Visible Light Communication,LED as Photo-receiver,LED as Photo-emitter,Indoor communication,Responsivity
更新于2025-09-12 10:27:22
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Growth of CdSe/MoS2 vertical heterostructures for fast visible-wavelength photodetectors
摘要： Heterostructures composed of different semiconducting materials have aroused wide attentions due to their fascinating properties originated from the interfaces. Particularly, the recent two dimensional layered materials (2DLM) have provided novel platforms to flexibly design the heterostructures for diverse electronic and optoelectronic applications. In this work, we have reported the growth of CdSe nanoplates/MoS2 monolayer vertical heterostructures with efficient and fast visible-wavelength photodetections. Highly dense CdSe nanoplates were vertically assembled on monolayer MoS2 through a two-step chemical vapor deposition (CVD) process. The interfacial photoinduced charge behaviors were investigated in detail via the time resolution photoluminescence (TRPL) measurements, revealing the efficient charge transfer across the heterointerface. Benefiting from the large CdSe coverage and efficient charge transfer, superior photodetection performances of the CdSe/MoS2 heterostructures can be obtained with an enhanced photoresponsivity of 1.63 A/W, which can be further improved to be 12 A/W via applying the gate voltage. Besides, the heterostructure detectors also exhibit a very fast photoresponse speed of 370 μs, much faster than previous photodetectors based on CVD-grown 2D heterostructures. The as-synthesized CdSe/MoS2 heterostructures may find important applications in integrated optoelectronic systems.
关键词： Responsivity,Chemical vapor deposition,Photodetectors,Vertical heterostructures,CdSe/MoS2
更新于2025-09-12 10:27:22
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A High‐Performance Solution‐Processed Organic Photodetector for Near‐Infrared Sensing
摘要： Sensitive detection of near-infrared (NIR) light enables many important applications in both research and industry. Current organic photodetectors suffer from low NIR sensitivity typically due to early absorption cutoff, low responsivity, and/or large dark/noise current under bias. Herein, organic photodetectors based on a novel ultranarrow-bandgap nonfullerene acceptor, CO1-4Cl, are presented, showcasing a remarkable responsivity over 0.5 A W?1 in the NIR spectral region (920–960 nm), which is the highest among organic photodiodes. By effectively delaying the onset of the space charge limited current and suppressing the shunt leakage current, the optimized devices show a large specific detectivity around 1012 Jones for NIR spectral region up to 1010 nm, close to that of a commercial Si photodiode. The presented photodetectors can also be integrated in photoplethysmography for real-time heart-rate monitoring, suggesting its potential for practical applications.
关键词： high responsivity,bulk heterojunctions,photodetectors,organic photodiodes,near-infrared
更新于2025-09-12 10:27:22
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High performance graphene-like thinly layered graphite based visible light photodetector
摘要： In this work, the drop casting method is utilized to obtain a thin graphene-like graphite layer as a photodetection layer on a SiO2/Si substrate, and its performance is characterized to determine its potential use in commercial applications. The thin layer is formed by first synthesizing graphite soot from a butane flame before being turned into a liquid solution and drop-casted onto the substrate to form a thin graphene-like graphite film. Field emission scanning electron microscope and Raman vibrational mode analyses indicate that the fabricated graphene-like graphite layer has characteristics similar to the graphene. The graphene-like graphite photodetector demonstrates a narrow photoresponse from 530 to 680 nm, covering visible sources from green to red. The responsivity and external quantum efficiency of the device under the illumination of red laser 660 nm is found to be around 148 mA W?1 and 27.8% respectively and is faster than that reported for similar systems using graphene and reduced graphene oxide previously. A fast response time of 83.7 and 28 μs at a modulation frequency of 1.0 and 10000 Hz respectively from the graphene-like thinly layered graphite photodetector shows potential application for the development of low-cost carbon-based photodetectors in near future.
关键词： Responsivity,Butane flame,Graphite,Frequency modulation,Photodetector
更新于2025-09-12 10:27:22
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Integration of MoS <sub/>2</sub> with InAlAs/InGaAs Heterojunction for Dual Color Detection in Both Visible and Near‐Infrared Bands
摘要： At present, dual-channel or even multi-channel recording is a developing trend in the field of photodetection, which is widely applied in environment protection, security, and space science and technology. This paper proposes a novel MoS2/InAlAs/InGaAs n–i–n heterojunction phototransistor by integrating multi-layered MoS2 with InGaAs-based high electron mobility transistors (InGaAs-HEMTs). Due to the internal photocurrent amplification in the InGaAs channels with a narrow energy bandgap of 0.79 eV, this device exhibits high photoresponsivity (R) of over 8 × 105 A W–1 under near-infrared illumination of 1550 nm at 500 pW. Furthermore, with the combination of the photoconductance effect in the vertical MoS2/InAlAs/InGaAs n–i–n heterojunction and the photogating effect in the lateral phototransistor, this device possesses a unique characteristic under visible illumination that its photoresponsivity can be tuned by the top gate electrode from 6 × 105 A W–1 to -4 × 105 A W–1 by gate voltage. This may lead to a new application as an optically controlled electronic inverter, which needs further study in depth. This MoS2/InAlAs/InGaAs phototransistor builds up a new bridge between 2D materials and conventional ternary compounded semiconductor devices.
关键词： MoS2/InAlAs/InGaAs van der Waals heterojunction,gate-tunable negative/positive responsivity,dual-band photodetection,2D electron gas
更新于2025-09-11 14:15:04
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Interface Defect Engineering for Improved Graphene-Oxide-Semiconductor Junction Photodetectors
摘要： The deeply depleted graphene-oxide-semiconductor (D2GOS) junction detector provides an effective architecture for photodetection enabling direct readout of photogenerated charge. Due to an inherent gain mechanism proportional to graphene’s high mobility (μ), this detector architecture exhibits large responsivities and signal-to-noise ratios (SNR). The ultimate sensitivity of the D2GOS junction detector may be limited, however, due to the generation of dark charge originating from interface states at the semiconductor/dielectric junction. Here, we examine the performance limitations caused by dark charge and demonstrate its mitigation via the creation of low interface defect junctions enabled by surface passivation. The resulting devices exhibit responsivities exceeding 10,000 A/W—a value which is 10x greater than that of analogous devices without the passivating thermal oxide. With cooling of the detector, the responsivity further increases to over 25,000 A/W, underscoring the impact of surface generation on performance and thus the necessity of minimizing interfacial defects for this class of photodetector.
关键词： 2D Materials,Photodetector,Interface Defects,GOS Junction,2D Detector,Graphene,High Responsivity
更新于2025-09-11 14:15:04
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A Bilayer 2D-WS2/Organic-Based Heterojunction for High-Performance Photodetectors
摘要： Two-dimensional (2D) tungsten disulfide (WS2) has inspired great efforts in optoelectronics, such as in solar cells, light-emitting diodes, and photodetectors. However, chemical vapor deposition (CVD) grown 2D WS2 domains with the coexistence of a discontinuous single layer and multilayers are still not suitable for the fabrication of photodetectors on a large scale. An emerging field in the integration of organic materials with 2D materials offers the advantages of molecular diversity and flexibility to provide an exciting aspect on high-performance device applications. Herein, we fabricated a photodetector based on a 2D-WS2/organic semiconductor materials (mixture of the (Poly-(N, N'-bis-4-butylphenyl-N, N'-bisphenyl) benzidine and Phenyl-C61-butyric acid methyl ester (Poly-TPD/PCBM)) heterojunction. The application of Poly-TPD/PCBM organic blend film enhanced light absorption, electrically connected the isolated WS2 domains, and promoted the separation of electron-hole pairs. The generated exciton could sufficiently diffuse to the interface of the WS2 and the organic blend layers for efficient charge separation, where Poly-TPD was favorable for hole carrier transport and PCBM for electron transport to their respective electrodes. We show that the photodetector exhibited high responsivity, detectivity, and an on/off ratio of 0.1 A/W, 1.1 × 1011 Jones, and 100, respectively. In addition, the photodetector showed a broad spectral response from 500 nm to 750 nm, with a peak external quantum efficiency (EQE) of 8%. Our work offers a facile solution-coating process combined with a CVD technique to prepare an inorganic/organic heterojunction photodetector with high performance on silicon substrate.
关键词： organic semiconductor,photodetector,responsivity,2D-WS2
更新于2025-09-11 14:15:04
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BiFeO3/CH3NH3PbI3 Perovskite Heterojunction Based Near-Infrared Photodetector
摘要： The paper reports a hybrid (i.e. organic-inorganic) perovskite CH3NH3PbI3 and inorganic only perovskite BiFeO3 based heterojunction diode for near-infrared detection applications. The hybrid halide CH3NH3PbI3 is synthesized by using sol-gel chemical route while the BiFeO3 is synthesized by using a solid-state route. A layer of uniformly distributed BiFeO3 thin film is first grown on an indium doped tin oxide (ITO) coated glass substrate using BiFeO3 nanoparticles with an average size of ~65 nm. Then, CH3NH3PbI3 nanoparticles of average size ~45 nm with a tetragonal phase are deposited BiFeO3 film for fabricating the heterojunction device under study. The photoresponse is measured by using a monochromatic light over the wavelengths from 400 to 900 nm. The device shows a dual-band photoresponsivity originated from the individual absorption characteristics of BiFeO3 and CH3NH3PbI3 the heterojunction. The proposed photodetector shows the maximum responsivity of ~2 A/W at 800 nm for 2 V bias while the detectivity is estimated as ~7.8×1012 cmHz1/2/W. The photodetector has a reasonably good photoresponse with a rise time and fall time of 0.74 s and 0.088 s, respectively.
关键词： Photodetector,Heterojunction,Responsivity,BiFeO3,Perovskite,CH3NH3PbI3
更新于2025-09-11 14:15:04