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Non-layered ZnSb nanoplates for room temperature infrared polarized photodetectors
摘要： Non-layered 2D ZnSb nanoplates are successfully synthesized by chemical vapor deposition, which possess narrow band gap and novel anisotropic properties. Infrared polarized photodetectors based on the ZnSb nanoplates are designed and exhibit high responsivity, fast photoresponse speed, great stability, high anisotropic conductivity and linear polarization sensitivity.
关键词： anisotropic properties,ZnSb nanoplates,narrow band gap,chemical vapor deposition,infrared polarized photodetectors
更新于2025-09-19 17:13:59
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Spatially Controlled Lateral Heterostructures of Graphene and Transition Metal Dichalcogenides toward Atomically Thin and Multi-Functional Electronics
摘要： Edge contacts between two-dimensional (2D) materials in the in-plane direction can achieve minimal contact area and low contact resistance, producing atomically thin devices with improved performance. Specifically, lateral heterojunctions of metallic graphene and semiconducting transition metal dichalcogenides (TMDs) exhibit small Schottky barrier heights due to graphene’s low work-function. However, issues exist with fabrication of highly transparent and flexible multi-functional devices utilizing lateral heterostructures (HSs) of graphene and TMDs via spatially controlled growth. This review demonstrates growth and electronic applications of lateral HSs of graphene and TMDs, highlighting key technologies controlling wafer-scale growth of continuous films for practical applications. It deepens the understanding of the spatially controlled growth of lateral HSs using chemical vapor deposition methods, and also contribute to the applications for the scale-up of all-2D electronics with ultra-high electrical performance.
关键词： electronic applications,graphene,lateral heterostructures,chemical vapor deposition,transition metal dichalcogenides
更新于2025-09-19 17:13:59
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Controlled Growth of Single‐Crystal Graphene Films
摘要： Grain boundaries produced during material synthesis affect both the intrinsic properties of materials and their potential for high-end applications. This effect is commonly observed in graphene film grown using chemical vapor deposition and therefore caused intense interest in controlled growth of grain-boundary-free graphene single crystals in the past ten years. The main methods for enlarging graphene domain size and reducing graphene grain boundary density are classified into single-seed and multiseed approaches, wherein reduction of nucleation density and alignment of nucleation orientation are respectively realized in the nucleation stage. On this basis, detailed synthesis strategies, corresponding mechanisms, and key parameters in the representative methods of these two approaches are separately reviewed, with the aim of providing comprehensive knowledge and a snapshot of the latest status of controlled growth of single-crystal graphene films. Finally, perspectives on opportunities and challenges in synthesizing large-area single-crystal graphene films are discussed.
关键词： single-crystal,graphene,grain boundaries,growth,chemical vapor deposition,nucleation
更新于2025-09-19 17:13:59
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Low-temperature chemical vapor deposition growth of graphene films enabled by ultrathin alloy catalysts
摘要： This report introduces a method for fabricating graphene at low temperatures via chemical vapor deposition enabled by ultrathin (～1 nm) nickel-gold (Ni-Au) catalysts. The unique combination of high carbon (C) solubility Ni, low C solubility Au, and an ultrathin layer of a catalyst demonstrates the effectiveness to produce graphene at 450 °C with the layer number independent of growth duration. In contrast to grain-boundary defined catalyst morphology found in thicker (>20 nm) metal catalysts, the ultrathin catalyst morphology leads to the formation of nanoscale metal “islands” during the growth process, which results in curved graphene covering the catalyst. To test the effect of preactivation of the ultrathin catalyst for the formation of graphene, a preanneal process of the catalyst followed by the introduction of a carbon precursor was also investigated. The preanneal process resulted in the formation of carbon nanotubes (CNTs) in lieu of graphene, displaying the impact of the catalytic surface treatment in relation to the produced materials. The results and discussion presented here detail a low-temperature nanoscale manufacturing process that allows for the production of either graphene or CNTs on an ultrathin catalyst.
关键词： graphene,low-temperature growth,nickel-gold catalysts,chemical vapor deposition,ultrathin alloy catalysts
更新于2025-09-19 17:13:59
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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Ultrathin Self-feeding Metasurface with Broadband Polarization Conversion and Electromagnetic Emission
摘要： A model for controlling the two-dimensional distribution of negatively charged nitrogen-vacancy (NV?) fluorescent centers near the surface of a diamond crystal is presented, using only a microwave plasma-assisted chemical vapor deposition (CVD) method. In this approach, a CVD diamond layer is homoepitaxialy grown via microwave plasma-assisted CVD using an isotopically enriched methane (12CH4 ), hydrogen (H2 ), and nitrogen (N2 ) gas mixture on patterned diamond (0 0 1). When the surface is imaged by means of confocal microscope photoluminescence mapping, fine grooves are observed to have been generated artificially on the diamond surface. NV? centers are found to be distributed selectively into these grooves. These results demonstrate an effective means for the formation of NV? centers of selectable size and density via microwave plasma-assisted CVD, with potential application in the production of diamond quantum sensors.
关键词： doping,nitrogen-vacancy centers,homoepitaxial,groove structure,Diamond,microwave plasma-assisted chemical vapor deposition
更新于2025-09-19 17:13:59
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Suppression of Parasitic Epitaxy Growth and Realization of High-Quality Wafer Surface Passivation of Silicon Heterojunction Solar Cells
摘要： Intrinsic hydrogenated amorphous silicon (i-a-Si:H) ?lms lead to excellent surface passivation of crystalline silicon wafers. However, a-Si:H deposition on a crystalline silicon wafer often results in undesired epitaxy growth, which deteriorates the passivation property, In this paper, we studied the in?uence of varying plasma enhanced chemical vapor deposition (PECVD) parameters, such as the product of the gas pressure (P ) and the electrode distance (Di) and the hydrogen dilution ratio (R = SiH4/(H2 + SiH4) × 100), on the passivation quality and the properties of silicon heterojunction (SHJ) solar cells. Measurements showed that proper combinations of high P ×Di and large R values can yield high minority carrier lifetimes (MCLTs) of passivated silicon wafers. Also, the tendency of MCLTs measured from passivated wafers is the same as that for open circuit voltages (Voc) of fabricated SHJ solar cells. A high Voc is obtained from SHJ solar cells when unwanted epitaxial growth is minimized at the wafer surface.
关键词： Plasma-enhanced chemical-vapor deposition,Amorphous semiconductors,Silicon solar cells,Heterojunctions
更新于2025-09-19 17:13:59
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Structural and mechanical characterization of carbon fibers grown by laser induced chemical vapor deposition at hyperbaric pressures
摘要： Laser induced chemical vapor deposition (LCVD) of freestanding carbon fibers from ethylene at hyperbaric pressures was investigated. Relationships between processing conditions, growth behavior, microstructure, and mechanical properties of the carbon fibers were established. It is found that the fiber growth rates are limited by surface reaction kinetics at low temperatures and limited by gas phase nucleation at high temperatures. At higher pressures and intermediate temperatures, growth becomes mass transport limited whereupon the fibers exhibit drastic changes in morphology and microstructure from a core-shell, smooth appearance to nodular formations. The tensile strengths of the carbon fibers grown by LCVD are generally poor due to the nature of graphitic carbon deposits. However, the Weibull modulus among the LCVD grown carbon fibers was found to be very high. Effects of processing conditions and microstructure on the fiber strengths are observed and discussed.
关键词： Microstructure,Hyperbaric pressures,Laser induced chemical vapor deposition,Carbon fibers,Mechanical properties
更新于2025-09-19 17:13:59
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Effect of bending test on the performance of CdTe solar cells on flexible ultra-thin glass produced by MOCVD
摘要： The development of lightweight and flexible solar modules is highly desirable for high specific power applications, building integrated photovoltaics, unmanned aerial vehicles and space. Flexible metallic and polyimide foils are frequently used, but in this work an alternative substrate with attractive properties, ultra-thin glass (UTG) has been employed. CdTe solar cells with average efficiency reaching 14.7% AM1.5G efficiency have been produced on UTG of 100 μm thickness. Little has been reported on the effects on PV performance when flexed, so we investigated the effects on J-V parameters when the measurements were performed in 40 mm and 32 mm bend radius, and in a planar state before and after the bend curvature was applied. The flat J-V measurements after 32 mm bending test showed some improvement in efficiency, Voc and FF, with values higher than the first measurement in a planar state. In addition, two CdTe solar cells with identical initial performance were subjected to 32 mm static bending test for 168 hours, the results showed excellent uniformity and stability and no significant variation on J-V parameters was observed. External quantum efficiency and capacitance voltage measurements were performed and showed no significant change in spectral response or carrier concentration. Residual stress analysis showed that no additional strain was induced within the film after the bending test and that the overall strain was low. This has demonstrated the feasibility of using CdTe solar cells on UTG in new applications, when a curved module is required without compromising performance.
关键词： Ultra-thin glass,Thin films,Metalorganic chemical vapor deposition,CdTe solar cells,Bending test
更新于2025-09-19 17:13:59
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MOCVD Growth and Characterization of InN Quantum Dots
摘要： Metal-polar InN quantum dots (QDs) are grown by metalorganic chemical vapor deposition at temperatures between 500 and 600 °C. Dot densities between 4 × 10^8 and 4 × 10^10 cm^-2 are observed. InN QDs exhibit room-temperature photoluminescence (PL) with peak wavelengths from 1100 to >1550 nm. GaN cap layers grown on InN QDs have little effect on either peak PL wavelength or intensity, a step toward creating multilayer structures for InN QD devices.
关键词： quantum dots,thin films,metalorganic chemical vapor deposition,nitrides
更新于2025-09-19 17:13:59
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Optical and electrical properties of fullerene C70 for solar cell applications
摘要： This research paper demonstrates the successful deposition of fullerene C70 for application as an acceptor material in Schottky barrier organic solar cell (OSC) device with structure fluorine-doped-tin-oxide/molybdenumtrioxide/fullerene/lithiumfluoride/aluminium (FTO/MoO3/C70/LiF/Al) using vapor thermal deposition technique. Morphology analysis using field emission scanning electron microscopy (FESEM) shows the mesoporous nature of highly cross-linked C70 molecules in deposited C70 thin film. But more uniform C70 film with less porosity has been deposited with high evaporation rate. We report the optical and electrical characterizations which reveal the thin film to be useful in photovoltaic applications. To study optical absorption spectra over visible energy range, prepared samples have been characterized by ultraviolet–visible (UV–vis) absorption spectroscopy. Optical dielectric parameters and dispersion properties of samples are studied. Constant Photocurrent Method (CPM) is employed to measure the mid gap absorption spectra of fabricated device. Defect density of states (DOS) distribution, Urbach energy and steepness parameter are also evaluated. Current-voltage characteristics of device in dark as well as under illumination surmise the behavior of device similar as Schottky barrier OSC.
关键词： Electrical properties,Optical properties,Fullerenes,Defects,Vapor deposition
更新于2025-09-19 17:13:59