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405?nm ultraviolet photodetector based on tungsten disulphide thin film grown by drop casting method
摘要： In this work, a tungsten disulphide or WS2 based heterojunction photodetector device is fabricated on top of Si substrate by simple drop casting. Raman shifts are observed at 350.16 and 419.36 cm?1, confirming the successful growth of the WS2 and the non-stoichiometric WS2 layers which are verified by energy-dispersive X-ray (EDX) spectroscopy. The device is characterized for its optoelectronic properties in the ultraviolet (UV) range of 405 nm. Current–voltage (I–V) measurement is performed to obtain the I–V curves of the photodiode under laser illumination at 30.219, 56.335, 80.457, 106.998 and 129.28 mW.cm?2. The photocurrent is found to be highly dependent on the laser power. The fabricated device has a high responsivity of 145.52 mA/W and a high detectivity of 1.248 × 1011 Jones for an incident laser power density of 129.28 mW.cm?2. These observed results are promising and indicate the viability of the proposed design for optoelectronic applications.
关键词： photodetector,UV,drop-casting,fall time,responsivity,WS2
更新于2025-09-19 17:13:59
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InGaAs/graphene infrared photodetectors with enhanced responsivity
摘要： High responsivity is a vital aim of photodetectors research. Based on the photogating effect, ultra-high responsivity can be realized by combining the high mobility of graphene and strong light absorption of other materials. Due to long carrier lifetime and low mobility, quantum dots(QDs) are usually used to form hybrid photodetectors with graphene. However, hybrid photodetectors of graphene with materials possessing higher mobility are rarely studied at present. In this paper, the hybrid photodetector of graphene and InGaAs is studied. We fabricated and measured pure InGaAs photodetectors, hybrid photodetectors of the whole graphene on InGaAs surface and hybrid photodetectors of graphene nanoribbons(GNRs) on InGaAs surface. It is found that, compared to pure InGaAs photodetectors, the responsivity of the whole graphene on InGaAs surface devices increases by 14.7 times, which is 7.66 A W?1, and the response time is twice faster. We also found that the negative back voltage can increase the photocurrent by modulating the Fermi energy of graphene and barrier height of the hybrid photodetectors. The illuminated area effect on various devices area was discussed in this study. In terms of theoretical mechanization, as high mobility materials, both graphene and InGaAs could generate and transport carriers in this hybrid photodetector under optical illumination. The photoexcited holes in InGaAs enter graphene while the photoexcited electrons in graphene enter InGaAs due to the built-in ?eld, which leads to a charge build-up on both sides of the junction and a strong photogating effect on the channel conductance. The results of this study are of novel signi?cance for the development of infrared detectors based on graphene.
关键词： infrared photodetectors,responsivity,graphene,InGaAs
更新于2025-09-19 17:13:59
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Wafer-size growth of 2D layered SnSe films for UV-Visible-NIR Photodetector Arrays with High Responsitivity
摘要： Due to its excellent electrical and optical property, tin selenide (SnSe), a typical candidate of two-dimentional (2D) semiconductors, has attracted great attention in the field of novel optoelectronics. However, the large-area growth of high-quality SnSe films still remain a great challenge which limit its practical applications. Here, wafer-size SnSe ultrathin films with high uniformity and crystallization are deposited via a scalable magnetron sputtering method. The results show that the SnSe photodetector is highly sensitive to a broad wavelength in the UV-Visible-NIR range, especially showing an extremely high responsivity of 277.3 A W -1 with the corresponding external quantum efficiency of 8.5×104% and detectivity of 7.6×1011 Jones. These figures-of-merits are among the best performance for the sputter-fabricated 2D photodetector devices. The photodetecting mechanisms based on a photogating effect induced by the trapping effect of the localized defects are discussed in details. The results indicate that the few-layered SnSe films from the sputtering growth would have great potential in designing high-performance photodetector arrays.
关键词： tin selenide,detectivity,responsivity,optoelectronics,SnSe,UV-Visible-NIR,2D semiconductors,external quantum efficiency,photodetector,magnetron sputtering
更新于2025-09-19 17:13:59
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Ultra-high responsivity (>12.34 kA/W) of ga-in bimetallic oxide nanowires based deep-UV photodetector
摘要： This work demonstrates the application of bimetallic oxide nanowires (NWs) for deep UV-photodetectors. The Ga-In based NWs has been fabricated by low cost and scalable electrospinning method. The fabrication process includes the synthesis of NWs on cleaned quartz substrate using electrospinning and followed by Al (100 nm)/Au (20 nm)-electrode deposition on top of the fine sheet of NWs. Owing to the very large surface to volume ratio, high porosity, photon trapping, and simultaneous front and back illumination, the fabricated bimetallic photodetector has shown a record ultra-high responsivity and the photo-dark current ratio of ~12348 AW-1 and ~298846 at 1 V bias respectively. The device has further revealed high detectivity ~3.27 × 1015 mHz0.5W-1 and external quantum efficiency ~7.73 × 106 %.
关键词： GaInO3,nanowires,bimetallic,ultra-high responsivity,UV-photodetector,electrospinning
更新于2025-09-19 17:13:59
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A remarkable effect of Pr doping on key optoelectrical properties of CdS thin films prepared using spray pyrolysis technique for high-performance photodetector applications
摘要： High-quality thin film-based photodetectors containing praseodymium doped cadmium sulfide (Pr:CdS) were fabricated through spray pyrolysis and studied for various opto-electrical applications. Field emission electron microscopy (FE-SEM) revealed that the prepared films were highly compacted with an extremely fine nanostructure without any pinhole or crack. X-ray diffraction and FT-Raman spectroscopy studies confirmed the single hexagonal phase of all the films. The crystallite size was found to lie between 19 and 32 nm. Optical spectroscopy revealed that the fabricated films have low absorbance and high transmittance (in range of 70–80%). The energy gap was found to lie in the range of 2.40–2.44 eV. The PL spectra contained an intense green emission band at ~531 ± 5 nm (2.33 eV), and its intensity was enhanced by increasing the Pr doping content in CdS. The dark and photo currents of CdS increased by approximately 950 and 42 times, respectively with the addition of 5.0 wt.% Pr. The responsivity (R) and specific detectivity (D*) were remarkably enhanced to 2.71 AW-1 and 6.9×1011 Jones, respectively, for the 5.0 wt.% Pr:CdS film. The external quantum efficiency (EQE) of 5 wt.% Pr:CdS films was 43 times that of pure CdS films, and the on/off ratio was 3.95 × 102 for 5.0 wt.% Pr:CdS film. Its high R, D*, and EQE values, and photo-switching behavior make Pr:CdS a good contender for high quality photodetector applications.
关键词： responsivity,external quantum efficiency,detectivity,CdS and Pr: CdS films,opto-electrical properties
更新于2025-09-19 17:13:59
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Role of nanowire length on the performance of self-driven NIR Photodetector based on mono/bi-layer graphene (camphor)/Si-Nanowire Schottky junction
摘要： In this article, we have demonstrated a solid carbon source such as camphor as a natural precursor to synthesize a large area mono/bi-layer graphene (MLG) sheet to fabricate nanowire junction based near infrared photodetectors (NIRPDs). In order to increase the surface-to-volume ratio, we have developed Si-nanowire arrays (SiNWAs) of varying lengths by etching up to 2V with a fast rise and decay time of 34/13 ms. A tremendous enhancement has been witnessed from 36 μA/W to 22 mA/W in the responsivity at 0V for MLG/30 min SiNWAs than planar Si. Then, the camphor based MLG/Si and MLG/SiNWAs schottky junction photodetectors have been fabricated to achieve efficient response with self-driven properties in the near infrared (NIR) regime. Due to a balance between light absorption capability and surface recombination centres, devices having SiNWAs obtained by etching for 30 min shows a better photoresponse, sensitivity and detectivity. Fabricated NIRPDs can also be functioned as self-driven device which are highly responsive and very stable at low optical power signals indicating an important development of self-driven NIRPDs based on camphor based MLG for future optoelectronic devices.
关键词： Si nanowire arrays,Graphene,Camphor,Responsivity and near infrared photodetectors.
更新于2025-09-19 17:13:59
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Photovoltaic activity of WSe2/Si hetero junction
摘要： Propelled by the development of layered transition metal dichalcogenides, heterojunctions have captivated tremendous attention due to various excitonic mechanisms assisted strong light-matter interaction. We demonstrate liquid phase exfoliation of WSe2 and fabrication of fast switchable WSe2/Si heterojunction. The heterojunction device showed obvious rectifying nature with ideality factor of 1.21 and it is explored under white illumination at power intensities varying from 5 to 18 mW/cm2. The WSe2/Si heterojunction photovoltaic device exhibited excellent transient photoresponse with highest responsivity of 86.11 mA/W and 23 ms response time under white light. Besides, heterojunction exhibited excellent photoresponse in broad spectral range from 390 to 1088 nm with highest photoresponsivity of 122.2 mA/W for 780 nm illumination. The device showed excellent response in temperature range 200 to 300 K. Eventually, the results advocate the huge significance of WSe2/Si heterojunction for photovoltaic cell and photodetection.
关键词： WSe2/Si heterojunction,Responsivity,Liquid phase exfoliation,Photovoltaic activity,Morse codes
更新于2025-09-16 10:30:52
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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) - A Graphene Self-Switching Diode Bridge Rectifier
摘要： Here we present theory and measurements for a bridge rectifier formed from arrays of graphene self-switching diodes (GSSDs). Graphene’s extremely high carrier mobility allows GSSDs to work at THz frequencies, with the bridge rectifier structure allowing for full wave rectification of an AC signal. We derive an equation for the voltage output of a GSSD bridge rectifier, predicting a quadratic dependence on input current. This relationship is confirmed using AC and DC measurements. The fabricated rectifier has a high room temperature intrinsic responsivity of 3,230 V/W at low frequency and a low noise equivalent power of 7.0 pW/Hz1/2. Moving forward, similar devices using CVD graphene have been tested and shown to function with high responsivity.
关键词： THz frequencies,responsivity,bridge rectifier,self-switching diodes,graphene
更新于2025-09-16 10:30:52
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Ultrasensitive broadband photodetector using electrostatically conjugated MoS2-upconversion nanoparticle nanocomposite
摘要： Hybrid or composite nanomaterials have emerged that demonstrates superior optoelectronic performance over pure nanomaterials that lacks broadband usage, or responsivity, or both, mainly because of the limitation of the collection of photogenerated carriers. We have addressed this problem by using a composite of MoS2 and a multi-photon absorbing lanthanide doped upconversion nanoparticles (UCNPs), that emits in the visible, to make a photodetector (PD) device with ultrahigh broadband responsivity. Single flake MoS2 electrostatically conjugated with UCNPs were used to fabricate the PD device with platinum, and gold contacts. The device was irradiated with UV-to-NIR illumination, at different power density, to study its broadband photosensitivity. Photoresponsivities in excess of 100 AW-1 is easily obtained; a highest responsivity of 1254 AW-1 is reported for 980 nm at 1.0 V bias. An unprecedented normalized gain of 7.12 x 10-4 cm2 V-1, and Detectivity of 1.05 x 1015 Jones (@980 nm, 1V) was obtained which is, to the best of our knowledge, the highest reported till date for this device class. Under vacuum conditions even higher values of these device parameters were obtained, while losing on the response speeds. The photoresponsivity in the nanocomposite followed the trend of the convoluted optical absorption of the individual components. Real application of the PD device was demonstrated using non-laser domestic appliances such as sodium vapour lamp, mobile phone flash light, and air-condition remote controller.
关键词： Nanocomposites,Responsivity,Molybdenum disulphide,Photodetectors,Broadband,Upconversion nanoparticles
更新于2025-09-16 10:30:52
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[IEEE 2019 16th International Conference on Quality in Research (QIR): International Symposium on Electrical and Computer Engineering - Padang, Indonesia (2019.7.22-2019.7.24)] 2019 16th International Conference on Quality in Research (QIR): International Symposium on Electrical and Computer Engineering - Room-Temperature Terahertz Antenna-Coupled Microbolometers with Titanium Thermistor and Heater
摘要： High-detectivity room-temperature terahertz (THz) detectors are expected to be utilized in spectroscopy and imaging for such applications as nondestructive inspection for safety, construction, noninvasive examination for medicine and pharmacy. We have studied THz antenna-coupled bolometers with titanium (Ti) thermistor and heater fabricated on a high-resistivity silicon (Si) substrate with MEMS structures in order to develop uncooled high-performance sensors. In this paper, we report the study on design, electromagnetic (EM) and thermal simulation, fabrication, experiment of THz-wave measurement, and evaluation of performance for single-detector devices, by which large THz array detectors are easily developed. We have achieved good performance as low noise-equivalent power (NEP) of the orders of 10-11 W/Hz1/2 and response frequency of 5.5 kHz by studying a Ti thermistor with thin meander line for the THz antenna-coupled bolometer.
关键词： nondestructive,terahertz (THz),meander line,sensing,thermistor,noise equivalent power (NEP),temperature coefficient of resistance (TCR),responsivity,bolometer,room temperature,uncooled,detector,array
更新于2025-09-16 10:30:52