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Effects of P-N Junction Built-In Electric Field on Ir-Led Resistance under Gamma Rays Irradiation
摘要： It is known that the rate of introduction of radiation defects into the Schottky barrier of GaAs and InP diodes depends on the presence of the electric field. The main aim of this research is to study the influence of the built-in electric field at the p-n junction on the resistance of dual AlGaAs heterostructure IR-LEDs under gamma rays irradiation. It is determined that the rate of defects introduction in the presence of built-in electric field or reverse bias at p-n junction is considerably less than the rate of defects introduction into the neutral region without electric field. Then the possible ways of improving the radiation resistance of infrared LEDs are considered.
关键词： heterostructures,p-n junction,AlGaAs,light emitting diodes,gamma ray
更新于2025-09-16 10:30:52
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Phenomenological Model of Radiation Hardness of LEDs Based on AlGaInP Heterostructures with Multiple Quantum Wells
摘要： Neutron degradation of LEDs based upon AlGaInP heterostructures (λ=630 nm and λ=590 nm) with multiple quantum wells are presented in the article. For the initial red LED (λ=630 nm) we can clearly distinguish three characteristic regions. In the small current region a low electron injection mode into the active region of the LEDs is observed. Further, as the operating current goes up, there are average and high electron injection in the active LEDs area regions. However, for the LEDY, the difference in the average and high electron injection regions is more pronounced and low electron injection region is absent. The boundary between the average and high electron injection regions can be characterized by the boundary current, which goes up with increasing exposure level. Three regions of electron injection in the active area of LEDs: low, average and high electron injection are illustrated for both types of LEDs under fast neutron irradiation. Based on the established relationships describing the emission power changing, a phenomenological model of the radiation hardness of LEDs based on AlGaInP heterostructures with MQW was shown. The LEDs radiation hardness is determined by the boundary current value, emission power in the low electron injection into the active LEDs area, the initial defective structure.
关键词： heterostructures,AlGaInP,Light emitting diodes
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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Monolayer MoSe <sub/>2</sub> /NiO van der Waals heterostructures for infrared light-emitting diodes
摘要： Nowadays monolayer transition metal chalcogenides (TMCs) have been widely researched due to their excellent optoelectronic properties. However, the preparation of large-sized monolayer TMCs and high-power TMC-based light-emitting diodes are still full of challenges, which limit their application in two-dimensional devices. Here, the large-sized monolayer single-crystalline MoSe2 was synthesized by chemical vapor deposition. The influence of the relative gas pressure ratio of MoO3 to Se on MoSe2 morphology is discussed. The TEM analysis confirmed the presence of 2H-phase monolayer MoSe2. A photoluminescence peak from the MoSe2 monolayer is detected at about 804 nm, illustrating an intrinsic energy bandgap of 1.54 eV. Importantly, a novel 2D/3D heterostructure, monolayer MoSe2/NiO van der Waals heterostructure, is constructed for a light-emitting diode (LED). The electroluminescence peaks of n-MoSe2/p-NiO LED locate at 812 nm, 848 nm and 918 nm, all of which are in the infrared light range. Interestingly, the electroluminescence peaks of our n-MoSe2/p-NiO LED are close to those of conventional air conditioner telecontrollers. So the n-MoSe2/p-NiO infrared LED is forward to be used in infrared remote sensing systems in the future.
关键词： van der Waals heterostructures,infrared light-emitting diodes,Monolayer MoSe2,chemical vapor deposition,NiO
更新于2025-09-16 10:30:52
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Pulsed laser synthesis of highly active Ag–Rh and Ag–Pt antenna–reactor-type plasmonic catalysts
摘要： Ag, Pt, and Rh monometallic colloids were produced via laser ablation. Separate Ag–Rh and Ag–Pt heterostructures were formed by mixing and resulted in groupings of Rh/Pt nanoparticles adsorbing to the concavities of the larger Ag nanostructures. The 400 nm Ag plasmonic absorption peak was slightly blue-shifted for Ag–Pt and red-shifted for Ag–Rh heterostructures. Catalytic activity for the reduction of 4-nitrophenol increased significantly for Ag–Pt and Ag–Rh compared to the monometallic constituents, and persisted at lower loading ratios and consecutive reduction cycles. The enhancement is attributed to the Rh and Pt nanoparticles forming antenna–reactor-type plasmonic catalysts with the Ag nanostructures.
关键词： Pt,catalysis,multicomponent,Rh,nanoparticles,antenna–reactor,4-nitrophenol,heterostructures,Ag,laser ablation,plasmonic
更新于2025-09-16 10:30:52
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Ultralow-Power Electrically Activated Lab-on-a-Chip Plasmonic Tweezers
摘要： We propose ultralow-power plasmonic tweezers with no external optical source. They consist of a one-dimensional array of graphene-based plasmonic units driven by the optical transitions within the underlying array of (Al, In)As/(Ga, In)As/(Al, In)As/(Ga, In)As/(Al, In)As quantum cascaded heterostructures (QCHs), electrically biased in series. Each QCH unit formed in a nanopillar can act as a built-in optical source required for exciting the localized surface plasmons (LSPs) at the surface of the overlying circular graphene nanodisk. The stimulated emission due to intersubband transition within each optical source evanesces through the top (Al, In)As cladding layer and interacts with the overlying graphene nanodisk, inducing the LSPs required for the formation of the plasmonic tweezers. Numerical simulations show, under 145–170 mV applied voltages, that the tweezers with graphene nanodisks of 16–30 nm in diameter and chemical potentials of 0.5–0.7 eV can trap polystyrene nanoparticles of 9 nm in diameter and larger, demonstrating acceptable sensitivities for variations in the nanoparticle diameter and refractive index. These lab-on-a-chip plasmonic tweezers, bene?ting from their small footprints and ultralow power consumptions, which are capable of sensing and trapping nanoparticles without requiring expensive external optical sources, open up a di?erent horizon for developing compact on-chip plasmonic tweezers.
关键词： plasmonic tweezers,localized surface plasmons,graphene,lab-on-a-chip,quantum cascade heterostructures
更新于2025-09-16 10:30:52
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Current Spreading Length and Injection Efficiency in ZnO/GaN-Based Light-Emitting Diodes
摘要： We report on carrier injection features in light-emitting diodes (LEDs) based on nonintentionally doped-ZnO/p-GaN heterostructures. These LEDs consist of a ZnO layer grown by chemical-bath deposition (CBD) onto a p-GaN template without using any seed layer. The ZnO layer (～1-μm thickness) consists of a dense collection of partially coalesced ZnO nanorods, organized in wurtzite phase with marked vertical orientation, whose density depends on the concentration of the solution during the CBD process. Due to the limited conductivity of the p-GaN layer, the recombination in the n-region is strongly dependent on the spreading length of the holes, Lh, coming from the p-contact. Moreover, the evaluation of Lh is not easy and generally requires the design and the fabrication of several LED test patterns. We propose a simple and effective method to calculate Lh, just based on simple considerations on I–V characteristics, and a way to improve the injection efficiency in the n region based on a noncircular electrode geometry. In particular, an interdigitated electrode structure is proved to be more efficient in terms of hole injection from n- to p-region.
关键词： zinc oxide (ZnO) nanorods,ZnO/GaN heterostructures,ZnO/GaN-based light-emitting diodes (LEDs),contact injection,current spreading length,Chemical-bath deposition (CBD)
更新于2025-09-16 10:30:52
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Heterostructures GaxIn1 –xAsyBizSb1 –y–z/InSb for Photodetector Devices
摘要： Isoparametric heterostructures GaxIn1 – xAsyBizSb1 – y – z/InSb for photodetectors operating in a 6- to 12-μ m wavelength interval have been manufactured by the method of floating-zone recrystallization with temperature gradient. The introduction of bismuth into GaInAsSb solid solution provides a decrease in bandgap width Eg, the corresponding increase in the working wavelength interval up to 12 μ m, and a shift in the photosensitivity maximum to longer wavelengths.
关键词： isoparametric heterostructures,photodetectors,IR detectors,absolute spectral sensitivity,volt–watt responsivity
更新于2025-09-16 10:30:52
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Observation of charge transfer in mixed-dimensional heterostructures formed by transition metal dichalcogenide monolayers and PbS quantum dots
摘要： We report an experimental study on charge transfer properties of mixed-dimensional heterostructures formed by zero-dimensional PbS quantum dots and two-dimensional transition metal dichalcogenides. Monolayers of MoSe2 and MoS2 were fabricated by mechanical exfoliation and chemical vapor deposition techniques, respectively. PbS quantum dots with diameters of 2.3 and 5 nm were synthesized by a hot-injection method and characterized by optical absorption spectroscopy and ultraviolet photoemission spectroscopy. The quantum dots were deposited on the MoS2 and MoSe2 monolayers to form heterostructures. Photoluminescence and transient absorption measurements were performed on the heterostructures as well as individual materials to reveal their photocarrier dynamics. We found that the holes excited in MoSe2 can efficiently transfer to both 2.3- and 5-nm PbS quantum dots, while electrons in these quantum dots cannot transfer to MoSe2. Similar charge transfer properties were observed between MoS2 and the 5-nm PbS quantum dots, while no charge transfer was observed between MoS2 and the 2.3-nm quantum dots. These results provide useful information for understanding the physical mechanism of charge transfer in mixed-dimensional heterostructures and for developing PbS quantum-dot-based mixed-dimensional materials.
关键词： PbS quantum dots,mixed-dimensional heterostructures,transition metal dichalcogenides,photocarrier dynamics,charge transfer
更新于2025-09-12 10:27:22
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Core–Shell‐Heterostructured Magnetic–Plasmonic Nanoassemblies with Highly Retained Magnetic–Plasmonic Activities for Ultrasensitive Bioanalysis in Complex Matrix
摘要： Herein, a facile self-assembly strategy for coassembling oleic acid-coated iron oxide nanoparticles (OC-IONPs) with oleylamine-coated gold nanoparticles (OA-AuNPs) to form colloidal magnetic–plasmonic nanoassemblies (MPNAs) is reported. The resultant MPNAs exhibit a typical core–shell heterostructure comprising aggregated OA-AuNPs as a plasmonic core surrounded by an assembled magnetic shell of OC-IONPs. Owing to the high loading of OA-AuNPs and reasonable spatial distribution of OC-IONPs, the resultant MPNAs exhibit highly retained magnetic–plasmonic activities simultaneously. Using the intrinsic dual functionality of MPNAs as a magnetic separator and a plasmonic signal transducer, it is demonstrated that the assembled MPNAs can achieve the simultaneous magnetic manipulation and optical detection on the lateral flow immunoassay platform after surface functionalization with recognition molecules. In conclusion, the core–shell-heterostructured MPNAs can serve as a nanoanalytical platform for the separation and concentration of target compounds from complex biological samples using magnetic properties and simultaneous optical sensing using plasmonic properties.
关键词： magnetic–plasmonic nanoassemblies,highly retained magnetic-plasmonic activities,core–shell heterostructures,lateral flow,self-assembly,immunoassays
更新于2025-09-12 10:27:22