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[IEEE 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Fukuoka, Japan (2019.7.7-2019.7.11)] 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Photonic Technology Improvements that Drives Future of LiDAR Applications
摘要： LiDAR is discussed based on principles of the direct time of flight (TOF) for automotive applications. 1D and 2D type Photon Counting photodetectors with ASIC were introduced as the future oriented long distance detection.
关键词： Semiconductor lasers,Photodetectors,Photonics-Electronics integration
更新于2025-09-16 10:30:52
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Interfacial engineering to boost photoresponse performance and stability of V2O5/n-Si heterojunction photodetectors
摘要： Transitional metal oxides (TMOs) have demonstrated as a promising alternative to doped layers in high-efficient crystalline silicon heterojunction solar cells. However, the unintentional oxidation causes serious carrier recombination at the interface, which accounts for the low photoelectric conversion efficiency and poor stability. Herein, a self-powered, broad-band, fast-response V2O5/n-Si heterojunction photodetectors (PDs) are fabricated by thermal evaporation of an ultrathin V2O5 thin films on nanoporous pyramid silicon structures. By interfacial engineering with structural optimization and surface methyl passivation, the photodetection performance and stability of V2O5/n-Si PDs can be significantly enhanced. The V2O5/n-Si heterojunction PDs demonstrate a high on/off ratio of 1.4×104, fast-response speed of 9.5 μs, high responsivity of 185 mA·W-1 (@940 nm) and high specific detectivity (1.34×1012 Jones). Based on the energy band alignment analysis, the excellent photoresponse performance is mainly attributed to the efficient carrier separation after surface passivation by methyl group. Additionally, the built-in electric field at the interface also accelerates the charge carrier separation. Our work would contribute to the fabrications of other TMOs-based heterojunctions, and give some enlightening insights into the understanding of carrier transportation in heterojunctions.
关键词： Carrier selective contact,Heterojunction photodetectors,Transition metal oxides,Interface engineering
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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Highly efficient broadband photodetectors based on lithography-free Au/Bi <sub/>2</sub> O <sub/>2</sub> Se/Au heterostructures
摘要： As one of the bismuth-based oxychalcogenide materials, Bi2O2Se ultrathin films have received intense research interest due to their high carrier mobility, narrow bandgaps, ultrafast intrinsic photoresponse and long-term ambient stability; they exhibit great potential in electronic and optoelectronic applications. However, the device performance of photodetectors based on metal/Bi2O2Se/metal structures has degraded due to the undesirable defects or contaminants from the electrode deposition or the sample transfer processes. In this work, highly efficient photodetectors based on Au/Bi2O2Se junctions were achieved with Au electrodes transferred under the assistance of a probe tip to avoid contaminants from traditional lithography methods. Furthermore, to improve the charge transfer efficiency, specifically by increasing the intensity of the electrical field at the Au/Bi2O2Se interface and along the Bi2O2Se channels, the device annealing temperature was optimized to narrow the van der Waals gap at the Au/Bi2O2Se interface and the device channel length was shortened to improve the overall device performance. Among all the devices, the maximum device photoresponsivity was 9.1 A W?1, and the device response time could approach 36 μs; moreover, the photodetectors featured broadband spectral responses from 360 nm to 1090 nm.
关键词： photodetectors,Au/Bi2O2Se/Au heterostructures,Bi2O2Se,broadband spectral responses
更新于2025-09-16 10:30:52
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A wearable helical organic–inorganic photodetector with thermoelectric generators as the power source
摘要： A self-powering feature is particularly appealing for wearable electronic devices when facing the challenges of energy and environmental crises. Photodetectors (PDs), as promising candidates for health and environment monitoring, are urgently desired to meet the requirements of being wearable and powerless. Unlike conventional photovoltaic-type PDs, we have come up with a novel approach to make a self-powered wearable PD, which involves connecting PDs with thermoelectric generators (TEGs) in series on the surface of a three-dimensional helical polymer substrate. The wearable system is light-weight, flexible and breathable. More importantly, compared with photovoltaic-type self-powered PDs, wearable PDs powered by TEGs will work as a system whose output signal can be greatly amplified by the temperature difference between the human body and the environment in winter when UV intensity is relatively low.
关键词： UV intensity,thermoelectric generators,self-powered,wearable electronic devices,photodetectors
更新于2025-09-16 10:30:52
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Nucleation-controlled growth of superior long oriented CsPbBr <sub/>3</sub> microrod single crystals for high detectivity photodetectors
摘要： There has been great interest in the use of cesium lead bromide (CsPbBr3), which is one of the most important members of the all-inorganic perovskite family, due to its superior optoelectronic performance and higher stability. Recently, it has been demonstrated that it is advantageous to use CsPbBr3 microrods and nanowires in photodetectors because of their higher crystallinity, low amount of defects, and easy control of carrier transport along a specific direction as compared to their counterparts of single crystals and thin films. However, there is a shortage of adequate investigations that describe how to control the growth of CsPbBr3 microrods and nanowires so that they retain the optoelectronic performance of single CsPbBr3 microrods. Therefore, we are reporting how to control the growth of orientated dispersive super-long CsPbBr3 microrod single crystals (CsPbBr3 MSCs) via a simple anti-solvent method. The crucial factor in controlling the growth of dispersive super-long CsPbBr3 MSCs is the regulation of the rapid nucleation rate and slowing of the growth rate via controlling the di?usion velocity of anti-solvent methanol. We also reveal the growth mechanism of CsPbBr3 MSCs as layer-by-layer growth that originates from the 2D nucleus. The CsPbBr3 MSCs are revealed grew in the direction of [010], with the (101) facet exposed. Moreover, photodetectors based on one CsPbBr3 MSC were fabricated, and the detectivity (D) and the on/o? ratio were as high as 3.67 (cid:2) 1012 Jones and 988, respectively, suggesting a very strong optoelectronic response as photodetectors. The mechanism that the Cs ions and Cs vacancies use to move to negative and positive electrodes along the channels constructed by [PbBr6]4(cid:3) in the [010] direction of the CsPbBr3 MSC (101) facet was revealed, after activation by the applied electrical field, which is beneficial to enhance the optoelectronic response but does not reduce the device stability.
关键词： anti-solvent method,optoelectronic performance,microrod single crystals,photodetectors,CsPbBr3
更新于2025-09-16 10:30:52
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Enhanced photocurrent in organic photodetectors by the tunneling effect of a hafnium oxide thin film as an electron blocking layer
摘要： To achieve high detectivity of organic photodetectors (OPDs), we investigated hafnium oxide (HfO2) as an electron blocking layer in an attempt to obtain a low leakage current and high photocurrent by the tunneling effect. The prepared devices consisted of indium tin oxide (ITO)/HfO2/(poly(3-hexylthiophene-2,5-diyl)[P3HT]:PC60BM)/Yb/Al. To explore the tunneling effect in a hafnium oxide thin film, we fabricated a thin film using successive ionic layer deposition. The results for hafnium oxide were compared with those for aluminum oxide and poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) (PEDOT:PSS). We found that hafnium oxide results in a low leakage current and high photocurrent owing to the tunneling effect in the OPDs. The resulting detectivity of 1.76 × 1012 Jones for a film thickness of 5.5 nm and bandwidth of ～100 kHz is suitable for commercialization.
关键词： detectivity,tunneling effect,organic photodetectors,hafnium oxide,electron blocking layer
更新于2025-09-16 10:30:52
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<i>In situ</i> synthesis of monolayer graphene on silicon for near-infrared photodetectors
摘要： Direct integration of monolayer graphene on a silicon (Si) substrate is realized by a simple thermal annealing process, involving a top copper (Cu) layer as the catalyst and an inserted polymethylmethacrylate (PMMA) as the carbon source. After spin-coating the PMMA carbon source on the Si substrate, the Cu catalyst was deposited on PMMA/Si by electron beam evaporation. After that, graphene was directly synthesized on Si by decomposition and dehydrogenation of PMMA and the catalyzation effect of Cu under a simple thermal annealing process. Furthermore, under an optimized growth condition, monolayer graphene directly formed on the Si substrate was demonstrated. Utilizing the as-grown graphene/Si heterojunction, near-infrared photodetectors with high detectivity ((cid:1)1.1 (cid:3) 1010 cm Hz1/2 W(cid:4)1) and high responsivity (50 mA W(cid:4)1) at 1550 nm were directly fabricated without any post-transfer process. The proposed approach for directly growing graphene on silicon is highly scalable and compatible with present nano/micro-fabrication systems, thus promoting the application of graphene in microelectronic fields.
关键词： thermal annealing,PMMA,silicon,photodetectors,copper catalyst,graphene
更新于2025-09-16 10:30:52
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P3HT-based visible-light organic photodetectors using PEI/PAA multilayers as a p-type buffer layer
摘要： A low leakage current is critical for achieving organic photodetectors (OPDs) with high detectivity. The insertion of buffer layers is an effective approach for reducing the reverse-biased leakage current. In this study, polyelectrolyte multilayers comprising polyethyleneimine (PEI) and polyacrylic acid (PAA) were introduced by a spin-assisted layer-by-layer technique into an OPD as a p-type buffer layer. Although PEI/PAA multilayers are insulators, when used as a buffer layer in our device, they suppressed the leakage current and also provided a high photocurrent due to the light-assisted tunneling effect. The prepared device configuration was ITO/(PEI/PAA)2/P3HT:PC60BM/Yb/Al. The performances of the OPDs were investigated by measuring the current–voltage characteristics, external quantum efficiency, and transient photocurrent. In addition, the operating mechanism of the OPDs was confirmed by impedance analysis. The device comprising (PEI/PAA)2 showed a specific detectivity of 3.11 × 1012 Jones and a bandwidth of 103.2 kHz at ?1 V and 525 nm. This performance is a numerical value that can be used in devices such as a line scan camera. In addition, because this device is fabricated by a low-temperature solution process, flexible and large-area substrates can be used.
关键词： light-assisted tunneling effect,organic photodetectors,PEI/PAA multilayers,p-type buffer layer,low-temperature solution process
更新于2025-09-16 10:30:52
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Complementary metal oxide semiconductor (CMOS) compatible gallium arsenide metal-semiconductor-metal photodetectors (GaAs MSMPDs) on silicon using ultra-thin germanium buffer layer for visible photonic applications
摘要： The monolithic integration of III–V materials on silicon appears as the most promising, cost-effective, and versatile method for next-generation optoelectronic devices. Here, we report on GaAs metal-semiconductor-metal photodetectors integrated on an Si substrate by metal-organic chemical vapor deposition. The device architecture is based on a GaAs active layer grown on Si via ultrathin, low-temperature Ge buffer layers. The Ge-on-Si acts as a “virtual” substrate to reduce the overall structural defects in the GaAs device layers. The metal-semiconductor junction characteristics were optimized to effectively suppress the dark current and passivate the interface defects. This was achieved through the insertion of an ultrathin Al2O3 interlayer at the metal/GaAs interface. The results show that a Schottky barrier height of 0.62 eV and 0.8 eV for electrons and holes, respectively, can be achieved. Circular devices with diameters ranging from 30 to 140 μm were fabricated. The measured room temperature dark current is ～48 nA for an applied reverse bias of 1.0 V and a device diameter of 30 μm. Additionally, the GaAs metal-semiconductor-metal structure exhibited a remarkable photoresponsivity and detectivity values of (0.54 ± 0.15) A/W and ～4.6 × 1010 cm Hz1/2 W?1 at 5 V reverse bias, 850 nm, respectively. The proposed method offers great potential for the monolithic integration of GaAs on an Si platform. Furthermore, this technique can be extended to other III–V materials and lattice mismatched systems for high-performance multiple band optoelectronics.
关键词： gallium arsenide,visible photonic applications,metal-semiconductor-metal photodetectors,germanium buffer layer,CMOS
更新于2025-09-16 10:30:52