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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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Plasmonic visible-NIR photodetector based on hot electrons extracted from nanostructured titanium nitride
摘要： The superior plasmonic characteristics of transition metal nitrides have been widely considered for enhancing the performance of light-harvesting devices. We explore this fast-emerging field further and report here the successful implementation of titanium nitride (TiN) nanoparticles prepared by reactive magnetron sputtering in a broadband photodetector device geometry. X-Ray Photoelectron Spectroscopy study reveals the presence of two different phases, viz., titanium nitride and titanium oxynitride in the prepared TiN sample. These two different nitride phases lead to two plasmon absorption bands, one in the visible region and the other in the Near Infrared (NIR) region of the electromagnetic spectrum, which is a fascinating finding of this study. The fabricated photodetector shows appreciable photoelectrical response in the visible as well as in the NIR region due to plasmon induced charge separation aided by the TiN nanoparticles. Very high photoresponsivities of 158 mA/W and 230 mA/W of the device at wavelengths of 450 nm and 950 nm, respectively, make it very promising as a broadband photodetector. The corresponding Internal Quantum Efficiencies are found to be 48% and 35%, respectively, at those two particular wavelengths. The charge transport mechanism of the device is explained with an energy level diagram, which shows that the hot electrons produced from the decay of plasmon are responsible for the generation of photocurrent.
关键词： photodetector,visible-NIR,hot electrons,plasmonic,titanium nitride
更新于2025-09-11 14:15:04
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Hot-electron photodetector with wavelength selectivity in near-infrared via Tamm plasmon
摘要： Tamm plasmonic (TP) structures, consisting of a metallic film and a distributed Bragg reflector (DBR), can exhibit pronounced light confinement allowing for enhanced absorption in the metallic film at the wavelength of the TP resonance. This wavelength dependent absorption can be converted into an electrical signal through the internal photoemission of energetic hot-electrons from the metallic film. Here, by replacing the metallic film at the top of a TP structure with a hot-electron device in a metal-semiconductor-ITO (M-S-ITO) configuration, for the first time, we experimentally demonstrate a wavelength-selective photoresponse around the telecommunication wavelength of 1550 nm. The M-S-ITO junction is deliberately designed to have a low energy barrier and an asymmetrical hot-electron generation, in order to guarantee a measurable net photocurrent even for sub-bandgap incident light with a photon energy of 0.8 eV (1550 nm). Due to the excitation of TPs between the metallic film in the M-S-ITO structure and the underlying DBR, the fabricated TP coupled hot-electron photodetector exhibits a sharp reflectance dip with a bandwidth of 43 nm at a wavelength of 1581 nm. The photoresponse matches the absorptance spectrum, with a maximum value of 8.26 nA/mW at the absorptance peak wavelength that decreases by more than 80% when the illumination wavelength is varied by only 52 nm (from 1581 to 1529 nm), thus realizing a high modulation wavelength-selective photodetector. This study demonstrates a high-performance, lithography-free, and wavelength-selective hot-electron near-infrared photodetector structure.
关键词： hot-electron photodetector,near-infrared,wavelength-selective photodetection,Tamm plasmonic structures,telecommunication wavelength
更新于2025-09-11 14:15:04
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All-Si Large-Area Photodetectors With Bandwidth of More Than 10 GHz
摘要： We report high-speed large-area silicon photodetectors (PDs) that were fabricated on silicon-on-insulator (SOI) substrates. These coplanar interdigital PDs were fabricated with finger spacing in the 0.5–5 μm range. One of the detectors, which had an area of 2300 μm2, achieved a bandwidth as high as 14.1 GHz under a bias voltage of ?10 V at a wavelength of 850 nm. Meanwhile, the device with the maximum area of 4300 μm2 also achieved a 7.9-GHz bandwidth, suggesting our detectors are highly suitable for high-speed 850-nm optical receiver for large area receiving applications. We established a new transition time and resistor–capacitor (RC) equivalent circuit model to analyze and calculate the 3-dB frequency of the coplanar interdigital PD; the model results were well-matched with the measurement results.
关键词： photodetector (PD),High-speed,silicon,large area
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) - Auckland, New Zealand (2019.5.20-2019.5.23)] 2019 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) - Experimental characterization of off-the-shelf LEDs as photodetectors for waking up microcontrollers
摘要： The use of LEDs as photodetectors has been subject of study for a long time. However, LEDs manufacturers do not provide information about the response of LEDs to the light. It is essential for the designers of electronic devices to know what the behavior of LEDs is so as to develop new applications in this area. In this work, we propose the use of commercially off-the-shelf LEDs, illuminated by the flashlight of a smartphone, as a contactless wake-up system for microcontrollers that are in a sleep mode. In particular, the generated LED voltage is proposed as the wake-up signal. So, in order to choose the most suitable LED and depending of the main interfering light, the current- voltage (I-V) characterization of different kind of LEDs is performed for two scenarios: outdoors and indoors. It is demonstrated that placing a resistor in parallel with the LEDs allows a better discrimination between the LED voltage coming from the flashlight and that from the interfering lights. Results show that red and blue LEDs are more appropriate for outdoor and indoor applications, respectively.
关键词： wake-up system,LED,photodetector,microcontroller
更新于2025-09-11 14:15:04
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Optimal Sphere-Sensor Ratio for Microsphere-Enhanced Photodetector Sensors in Cameras/Telescopes with and without Central Obscuration
摘要： A microsphere lens on top of a photodetector sensor increases its sensitivity and reduces its Noise-to-Signal Ratio (NSR), as shown in our previous work. This paper discusses a methodology to determine the optimal sphere-sensor ratio, in terms of increased current sensitivity, for microsphere-lens-enhanced photodetectors, using computational analysis including a modeling, with an experimentally derived photo-detector sensor responsivity and simulation setup that emulates conditions generally found within cameras and telescopes. In particular, we study and analyze the effect that several variables have on such ratios. We focus on variables such as microsphere material type, photodetector type, light source temperature, and in the case of reflective telescopes, central obscurations from a secondary mirror. Results of the effect of microsphere-sensor misalignment on such ratios are also presented. As we show in this paper, since the optimized ratio is dependent on a given wavenumber considered, therefore the proposed methodology uses an integral optimization over a given spectral band to derive the optimized ratio over that band. Some of our findings show, for the first time, that the optimal ratio is virtually independent of a given central obscuration. Finally, we demonstrate here the flexibility of the proposed methodology in showing performances of microsphere-enhanced photodetector sensors.
关键词： central obscuration,computational analysis,current sensitivity,photodetector sensor,optimal sphere-sensor ratio,microsphere lens
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
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[IEEE 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Miramar Beach, FL, USA (2019.8.19-2019.8.21)] 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - 2D TMDCs-Based NIR Photodetector on a Silicon Microring Cavity
摘要： Here, we report a photodetector (PD) based on heterogeneous integration of Few-layer MoTe2 integrated on MRR by using our developed 2D printer technique. The device is realized in a two-terminal in-plane electrode configuration without applying external gating, showing a responsivity of (~0.1 A/W).
关键词： TMDCs,micro-ring resonator,photonic integration,2D materials,photodetector
更新于2025-09-11 14:15:04
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Two-Color Photodetector for the Visible Spectral Range Based on ZnSe/ZnS/GaAs Bragg Reflector
摘要： Effect of the ZnSe/ZnS/GaAs distributed Bragg reflector (DBR) on the parameters of the spectral response of a photodiode based on rectifying contacts in the metal–semiconductor–metal (MSM) system is studied. The calculated photoreflection spectra of the ZnSe/ZnS/GaAs heterostructure are in good agreement with the experimental data. It is shown that the MSM diode provides two-color response of the photodetector at wavelengths of 420 and 472 nm, a sharp decrease in the photosensitivity in the long-wavelength part of the response signal, high quantum efficiency (53%), and low dark current (5 × 10–10 A). It is demonstrated that the narrow-band two-color response of the detector can be tuned to the desired wavelength using appropriate selection of the parameters of the heterostructure that forms that Bragg reflector.
关键词： two-color photodetector,quantum efficiency,MSM diode,distributed Bragg reflector,ZnSe/ZnS/GaAs
更新于2025-09-11 14:15:04
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MAPbI3 nanowires prepared by a facile Vapor Transfer Method for simple photodetector
摘要： MAPbI3 nanowires have become one of the promising materials for optoelectronic devices. Herein, a simple template-free vapor transfer approach to synthesize MAPbI3 nanowires on various substrates for optoelectronic device developed. High crystalline MAPbI3 nanowires were realized via methyl-ammonium iodide (MAI) vapor transfer treatment with PbI2 nanowires. PbI2 nanowires were prepared by a self-assembled procedure where PbI2 film was recrystallized and converted to nanowires structure with the exposure of dimethylacetamide (DMAC) vapor. On top of that, the density of MAPbI3 nanowires could be modulated by simply tuning the thickness of PbI2 film. The as-fabricated MAPbI3 nanowires photodetector exhibits a satisfying responsivity of 0.115 A W-1 @3V while the rise time is less than 0.63 s and the decay time is less than 0.73 s. The study presents a bright future of MAPbI3 nanowires for optoelectronic application.
关键词： vapor transfer method,organic mixed halide perovskite,nanowires,nanocrystalline materials,photodetector,sensors
更新于2025-09-11 14:15:04