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Selective Growth of Ordered Hexagonal InN Nanorods
摘要： Well-ordered and vertically aligned InN nanorods with high aspect ratio are synthetized by hydride vapor phase epitaxy (HVPE) using the selective area growth (SAG) approach. The growth occurs through the apertures of a SiNx masked Ga-polar GaN/c-Al2O3 template for adjusted growth temperature and V/III ratio. The nanorods exhibit a hexagonal shape without any rotation around the growth axis. The wurtzite structure and the high crystalline quality of InN nanorods are confirmed by X-ray diffraction (XRD) as well as by high-resolution transmission electron microscopy (HR-TEM). Only few stacking faults are identified at the bottom part of the nanorods. Photoluminescence (PL) displays an emission peak centered at 0.77 eV which agrees with the band gap of InN. These promising achievements, which go far beyond the existing InN growth limitations, pave the way towards the integration of pure InN in future devices
关键词： Selective Area Growth,Hydride Vapor Phase Epitaxy,Indium Nitride,Nanorods
更新于2025-11-21 11:03:13
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Architectural Design of Photodetector Based on 2D (MoS <sub/>2</sub> ?Nanosheets)/1D (WS <sub/>2</sub> ?Nanorods) Heterostructure Synthesized by Facile Hydrothermal Method
摘要： Hydrothermal technique is utilized to synthesize 2D/1D heterostructure based on MoS2 (nanosheets)/WS2 (nanorods) for photodetector application. The sensor was fabricated by drop cast technique. X-Ray Diffraction (XRD), Fourier Transform Infra-red (FTIR) Spectroscopy, Field-Emission Scanning Electron Microscopy (FESEM), UV-Visible (Uv-Vis), Raman and X-Ray Photoelectron spectroscopy (XPS) were performed to characterize the synthesized sample. The optical sensor based on heterostructure was studied as a function of laser wavelength (λex): 635 nm (red), 785 nm (infra-red) and 1064 nm (near infra-red) and power of illuminated laser sources. The device exhibits photoresponsivity in a broadband range from the visible to the near-infrared (600–1065 nm, yield a photoresponsivity (Rp) = 15 μA/W and high speci?c detectivity (D?) = 24 × 106 jones at λex = 785 nm). The photoresponsive characteristics of MoS2/WS2 heterostructure hold the principle of simple power law.
关键词： MoS2 nanosheets,photodetector,hydrothermal method,WS2 nanorods,2D/1D heterostructure
更新于2025-11-21 11:01:37
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Tailoring optical cross sections of gold nanorods at a target plasmonic resonance wavelength using bromosalicylic acid
摘要： In many applications, the optical cross sections of gold nanorods (AuNRs) are required to be tailored at a fixed target longitudinal surface plasmon resonance (LSPR) wavelength depending on the excitation source and the photodetector. In this work, we demonstrate the fine tailoring of optical cross sections of AuNRs at a fixed target resonance wavelength, on the basis of AuNR overgrowth using a binary surfactant mixture consisting of 5-bromosalicylic acid (BSA) and cetyltrimethylammonium bromide (CTAB). A systematic study was performed on the sum effects of the BSA concentration and the volume of the growth solution, which gives a formula for quantitative instructions. Based on the formula, we gave examples for the successful synthesis of AuNRs with different optical cross sections at target LSPR wavelengths. From simulation, a nonlinear relationship was further derived to understand the relationship between the aspect ratio and the width of the AuNRs at a target LSPR wavelength for the dimension design of AuNRs. The ratio of optical against physical cross sections was calculated and plotted as a function of the width. The results clearly indicate that AuNRs with a width of 30 nm possess the highest efficiency in terms of optical per physical cross section. Our study provides reliable methods for the synthesis, as well as guidelines for the dimension design of AuNRs, for use in a variety of applications.
关键词： 5-bromosalicylic acid,gold nanorods,optical cross sections,cetyltrimethylammonium bromide,surface plasmon resonance
更新于2025-11-19 16:56:42
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Eu3+/Yb3+ co-doped gadolinium oxysulfide upconverting nanorods: Morphological, physicochemical and optical evaluation
摘要： In this study, we introduce a novel route to produce down and upconverting Eu3t/Yb3t co-doped oxysul?de nanorods, which display strong red emission at 620 nm under Vis (460 nm) or NIR (976 nm) wavelength excitation. An in-depth analysis of the synthesis parameters such as lanthanides concentration, type of nucleating agent, reaction temperature, and the reaction pressure was performed to determine their in?uence in the morphology and photoluminescence properties. It was demonstrated that as a nucleating agent, ethanolamine is a good substitute of the commonly used triethylamine providing the advantage of using lower toxicity reagents. The Transmission Electron Microscopy (TEM), Infrared (FTIR) and Zeta Potential analysis showed that the chemical surface of nanorods evolve during thermal and sul?dation processes without producing morphological changes. The intensity of light emission during downconversion (DC) and upconversion (UC) phenomena was found to be doping ions concentration dependent. The highest DC light emission was found at a Yb3t/Eu3t concentration ratio of 0.25, while the most intense UC luminescence was found at 4. Conversely, quenching of DC and UC was observed when using Yb3t/Eu3t concentration ratios of 4 and 0.25 respectively, indicating that luminescent centers are strongly affected in both processes by the chemical environment but also for the ions doping ratio. It was demonstrated that two-photon absorption is the primary mechanism for the red emission in the UC process.
关键词： Nanorods,Rare earth alloys and compounds,Upconversion,Oxysul?de
更新于2025-11-19 16:56:35
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Photocatalytic and Antimicrobial Properties of Ga Doped and Ag Doped ZnO Nanorods for Water Treatment
摘要： Water contamination is a worldwide concerning problem. Emerging contaminants have made conventional water treatment processes ineffective. This makes the search for new materials with improved physical-chemical properties for water treatment an urgent necessity. Doping metal oxides nanostructures can improve the photocatalytic degradation of contaminants and the antimicrobial activity of the material. During this process, water treatment not only involves the degradation of toxic pollutants, but also the elimination of virus and bacteria. Then, it is important to study not only the effect of a dopant in a material as photocatalyst but also the effect in its antimicrobial properties. In this work ZnO nanorods, Ga doped ZnO nanorods and Ag doped ZnO nanorods are synthesized and supported in polyethylene by a fast-hydrothermal microwave heating synthesis. Their photocatalytic performance and antimicrobial properties for water treatment were evaluated. Experiments show that Ag and Ga can improve the photocatalytic and antimicrobial properties of ZnO nanorods; the relationship between doping concentrations, with both the toxicity effect of the nanorods toward bacteria and the nanorods photocatalytic performance, is shown.
关键词： doping,water,antimicrobial,nanorods,contamination,metal oxide,photocatalysis,zinc oxide
更新于2025-11-19 16:56:35
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Femtosecond Pulse Laser Near-Field Ablation of Ag Nanorods
摘要： Ag nanorods (Ag NRs) with a mean aspect ratio of 3.9 were prepared through a wet-chemical method, and the absorption spectra for various aspect ratios were obtained. The morphology transformation of Ag NRs irradiated with a femtosecond pulse laser was investigated through transmission electron microscopy (TEM). The near-field ablation was dependent on the laser polarization and wavelength. Laser-induced high electric field intensity was observed at the ends, middle, and junctions of the Ag NRs under various ablation conditions. Through simulation, the evolution mechanism was analyzed in detail. The effect of laser polarization angle on plasmonic junction welding was also investigated. By controlling the electronic field distribution, several nanostructures were obtained: bone-shaped NRs, T-shaped NRs, dimers, trimers, curved NRs, and nanodots. This study suggests a potentially useful approach for the reshaping, cutting, and welding of nanostructures.
关键词： femtosecond pulse laser,polarization,Ag nanorods,near-field ablation
更新于2025-11-14 17:04:02
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ZIF-8@H:ZnO Core-shell nanorods arrays/Si heterojunction self-powered photodetector with ultrahigh performance
摘要： The native defects will degrade the performance and stability of the optoelectric device. Herein, a zeolitic imidazolate framework-8 (ZIF-8)@H:ZnO core-shell nanorods arrays/Si heterojunction self-powered photodetector is demonstrated. Combining hydrogenation and ZIF-8 passivation, its photoresponsive characteristics are greatly enhanced. The photodetector exhibits superior detectivity of ~2.14×1016 Jones (1 Jones=1 cm Hz1/2 W-1), high responsivity of ~7.07×104 mA W-1, prominent sensitivity of ~2.08×1012 cm2 W-1 and broadband photodetection ranging from the ultraviolet to the near infrared. As critical figures of merit, its responsivity increases by nearly 5 orders of magnitude than that of pristine ZnO nanorods arrays/Si heterojunction photodetector. More importantly, the comprehensive performance of ZIF-8@H:ZnO core-shell nanorods arrays/Si heterojunction photodetector not only achieves a record high value for ZnO-based photodetectors reported so far, but also can be comparable with that of two-dimensional (2D) materials, zero-dimensional (0D) materials, topological insulators, perovskites and other oxides based self-powered photodetectors. The novel post-treatment strategy has great potential in developing high-performing self-powered photodetectors. Meanwhile, this work may be extended to other oxides based optoelectronic devices.
关键词： core-shell nanorods,heterojunction,passivation,self-powered photodetector,ZnO,ZIF-8,hydrogenation
更新于2025-11-14 17:04:02
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The impact of ZnO configuration as an external layer on the sensitivity of a bi-layer coated polymer optical fiber probe
摘要： Salinity magnitude changes are a critical factor for determining the chemistry of natural water bodies and biological processes. Label-free refractive index sensors are promising devices for detecting these changes. A polymer optical fiber (POF) sensor modified with cladding treatment and a bi-layer zinc oxide/silver (ZnO/Ag) nanostructure coating to determine sodium chloride concentration changes through refractive index variations in water is experimentally demonstrated. The use of three ZnO nanostructure shapes, nanoparticles and horizontally and vertically oriented nanorods, as an external layer and a broad spectrum light source from the visible (Vis) to the near infrared (NIR) region are investigated to achieve optimum sensitivity. The rms roughness, optical band-gap and zeta potential (ZP) value for the vertically oriented sample are 148 nm, 3.19 eV and 5.96 mV, respectively. In the NIR region the wavelength–intensity sensitivity values of probes coated with ZnO nanoparticles and horizontally and vertically oriented nanorods are 104 nm RIU?1–12 dB RIU?1, 63 nm RIU?1–10 dB RIU?1 and 146 nm RIU?1–22 dB RIU?1, respectively, and in the Vis area the values are 65 nm RIU?1–14 dB RIU?1, 58 nm RIU?1–11 dB RIU?1 and 89 nm RIU?1–23 dB RIU?1, respectively. The maximum amplitude sensitivity is obtained for the probe coated with vertically aligned ZnO nanorods in the NIR area due to the deeper penetration of evanescent waves, a higher surface-volume ratio, better crystallinity, more adhesive interactions with salt molecules, larger surface roughness and higher-order dispersion compared to the other coated ZnO nanostructures.
关键词： sensitivity,salinity,nanorods,refractive index sensors,ZnO/Ag nanostructure,polymer optical fiber,nanoparticles
更新于2025-11-14 15:25:21
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Graphene oxide/ZnO nanorods/graphene oxide sandwich structure: The origins and mechanisms of photoluminescence
摘要： In this paper, we present the structural and optical properties of Graphene oxide/ZnO nanorods/graphene oxide (GO/ZnO nanorods/GO) nanocomposites prepared via a hydrothermal method on Si (100) substrate. The X-ray diffraction measurements (XRD) confirm that the prepared samples are of hexagonal wurtzite structure with crystallite size around 50-60 nm. It was obvious from scanning electron microscopy (SEM) that by incorporating the ZnO nanorods between the inter-layer of GO confirmed the formation of sandwich-like nanocomposites structure. ZnO nanorods interaction with GO is displayed by the different vibrational frequencies in fourier transform infrared spectroscopy (FTIR). The UV-Vis spectrum reveals the strongest absorption was observed around 370 nm, while calculating optical band gap energy (Eg) of GO/ZnO NRs/GO was found to be 3.15 eV. The photoluminescence (PL) measurements indicates that the ZnO nanorods have a strong visible emission centered at 559 nm attributed to the presence of impurities in the form of oxygen vacancies. After the nanorods were covered with GO layers, the PL intensity of the nanocomposite is quenched and shifted due to charge-transfer process. Consequently, the obtained results may lead to better performance for the optoelectronic applications.
关键词： ZnO nanorods,hydrothermal method,excitation effect,graphene oxide
更新于2025-11-14 15:25:21
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Facile enhancement of bulk heterojunction solar cells performance by utilizing PbSe nanorods decorated with graphene
摘要： An efficient approach for improving the photoelectrical conversion efficiency (PCE) of the bulk heterojunction (BHJ) solar cells, based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61 butyric acidmethyl ester (PC61BM), by the incorporating PbSe nanorods decorated with graphene (G) into their active layer has been reported for the first time. Pristine PbSe and PbSe:G composites (with different amount of graphene) are synthesized via hydrothermal process and the formation mechanism is explained. The systematic investigation indicates that the crystallite size of PbSe:G increases with increasing graphene content. The PCE of the classical BHJ solar cells based on P3HT:PC61BM is improved from 2.32 up to 2.57 % by the incorporation of pristine PbSe. It is also enhanced by the incorporation of PbSe:G up to certain composition of graphene in which a maximum PCE value of 5.16 % is achieved. The external quantum efficiency of the BHJ solar cells is also investigated. The photovoltaic parameters are discussed based on the morphology variation detected by scanning electron microscope and atomic force microscope of the active layer together with their UV-VIS absorption measurements.
关键词： Graphene,optical absorption,PbSe nanorods,surface morphology,BHJ solar cells
更新于2025-10-22 19:40:53