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Design and Operation of an Optically-Accessible Modular Reactor for Diagnostics of Thermal Thin Film Deposition Processes
摘要： The design and operation of a simple, optically-accessible modular reactor for probing thermal thin film deposition processes, such as atomic layer deposition processes (ALD) and chemical vapor deposition (CVD), is described. This reactor has a nominal footprint of 225 cm2 and a mass of approximately 6.6 kg, making it small enough to conveniently function as a modular component of an optical train. The design is simple, making fabrication straightforward and relatively inexpensive. Reactor operation is characterized using two infrared absorption measurements to determine exhaust times for tetrakis(dimethylamino)titanium and water, proto-typical ALD precursors, in a pressure and flow regime commonly used for ALD.
关键词： ALD,atomic layer deposition,in situ,reactor,diagnostics,chemical vapor deposition,CVD,optical cell
更新于2025-09-23 15:21:21
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Effect of low-energy ion impact on the structure of hexagonal boron nitride films studied in surface-wave plasma
摘要： A high‐density surface‐wave plasma source is used to deposit hexagonal boron nitride (hBN) films in a gas mixture of He, H2, N2, Ar, and BF3 under a high ion flux condition using low‐energy ion irradiation. The ion energy is controlled between around zero and 100 eV by applying a negative or positive bias voltage to a substrate, while the ion flux is increased by locating a substrate upstream in the diffusive plasma. For ion energies above ～37 eV, the structure of the films depends upon ion energy more than substrate temperature, typical of subplantation processes. As a result, the structural order and crystallinity of sp2‐bonded phase in the films characterized by Fourier transform infrared spectroscopy and X‐ray diffraction are increased with decreasing ion energy, while the mass density of the films characterized by X‐ray reflectivity is retained relatively high with a slight dependence upon ion energy.
关键词： surface‐wave plasma,Fourier transform infrared spectroscopy (FTIR),chemical vapor deposition (CVD),hexagonal boron nitride (hBN),X‐ray diffraction (XRD),X‐ray reflectivity (XRR)
更新于2025-09-23 15:21:21
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Nonlinear Optical Properties of CdS Semiconductor nanowires
摘要： In this work, we report on the nonlinear optical properties in single Cadmium sulfide nanowires (CdS NWs). The high qulity growth of CdS semiconductor nanowires were synthesized by chemical vapor deposition (CVD) method. The as-obtained products were characterized by X-ray diffraction (XRD) , Scanning electron microscopy (SEM), and the energy dispersive X-ray spectrom (EDS) was used to determine the specific elemental distribution and show purity of the CdS semiconductor nanowires . The excitation of femtosecond laser(800 nm, 50 fs, 80 MHz) was used to study the nonlinear optical properties of CdS nanowires, such as the Second Harmonic Generation(SHG) and optical waveguide effect. CdS NW has a second harmonic generation with a blue emission bands at a wavelength of 400 nm . Finally, based on the dark field image of the CCD taken and combined with the spectrum, it is proved that CdS NW has an optical waveguide effect.
关键词： Cadmium sulfide (CdS),Waveguide,nanowires (NWs),Second- Harmonic Generation (SHG),Chemical Vapor Deposition (CVD)
更新于2025-09-19 17:15:36
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Single Crystal Diamond Deposited by Dual Radio-Frequency Plasma Jet CVD with High Growth Rate
摘要： Single crystal diamonds were deposited on high pressure high temperature (HPHT) substrate with high growth rate, up to 18.5 μm/h, by using dual radio-frequency inductive coupled plasma jet. The methane ?ux was found to in?uence the growth rate of single crystal diamond. The reason for this might be ascribed to the electron temperature increase, raising the ?ux of methane, based on the plasma diagnosis results by optical emission spectra (OES). The results of Raman spectroscopy and the X-ray rocking-curve indicated that as-deposited diamonds are of good quality.
关键词： growth rate,single crystal diamond,methane ?ux,dual radio frequency,chemical vapor deposition (CVD),inductive coupled plasma jet
更新于2025-09-19 17:15:36
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Synthesis of Monolayer MoSe2 with Controlled Nucleation via Reverse-Flow Chemical Vapor Deposition
摘要： Two-dimensional (2D) layered semiconductor materials, such as transition metal dichalcogenides (TMDCs), have attracted considerable interests because of their intriguing optical and electronic properties. Controlled growth of TMDC crystals with large grain size and atomically smooth surface is indeed desirable but remains challenging due to excessive nucleation. Here, we have synthesized high-quality monolayer, bilayer MoSe2 triangular crystals, and continuous thin films with controlled nucleation density via reverse-flow chemical vapor deposition (CVD). High crystallinity and good saturated absorption performance of MoSe2 have been systematically investigated and carefully demonstrated. Optimized nucleation and uniform morphology could be achieved via fine-tuning reverse-flow switching time, growth time and temperature, with corresponding growth kinetics proposed. Our work opens up a new approach for controllable synthesis of monolayer TMDC crystals with high yield and reliability, which promote surface/interface engineering of 2D semiconductors towards van der Waals heterostructure device applications.
关键词： controlled growth,transition metal dichalcogenides (TMDCs),MoSe2,reverse-flow chemical vapor deposition (CVD)
更新于2025-09-16 10:30:52
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Renewable and Sustainable Composites || Methodologies for Achieving 1D ZnO Nanostructures Potential for Solar Cells
摘要： One-dimensional (1D) nanostructures are generally used to describe large aspect ratio rods, wires, belts, and tubes. The 1D ZnO nanostructures have become the focus of research owing to its unique physical and technological significance in fabricating nanoscale devices. When the radial dimension of the 1D ZnO nanostructures decreases to some lengths (e.g., the light wavelength, the mean of the free path of the phonon, Bohr radius, etc.), the effect of the quantum mechanics is definitely crucial. With the large surface-to-volume ratio and the confinement of two dimensions, 1D ZnO nanostructures possess the captivating electronic, magnetic, and optical properties. Furthermore, 1D ZnO nanostructure’s large aspect ratio, an ideal candidate for the energy transport material, can conduct the quantum particles (photons, phonons, electrons) to improve the relevant technique applications. To date, many methods have been developed to synthesize 1D ZnO nanostructures. Therefore, methodologies for achieving 1D ZnO nanostructures are expressed, and the relevant potential application for solar cells are also present to highlight the attractive property of 1D ZnO nanostructures.
关键词： hydrothermal,nanostructures,one dimensional,ZnO,solar cell,chemical vapor transport and condensation (CVTC),vapor-liquid-solid (VLS),electrochemical,metal-organic chemical vapor deposition (MOCVD),chemical vapor deposition (CVD)
更新于2025-09-11 14:15:04
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Quantum Multibody Interactions in Halide-Assisted Vapor-Synthesized Monolayer WSe <sub/>2</sub> and Its Integration in a High Responsivity Photodetector with Low-Interface Trap Density
摘要： Among the two-dimensional (2D) transitional-metal dichalcogenides, monolayer (1L) tungsten diselenide (WSe2) has recently attracted a great deal of interest because of its direct band gap and tunable charge transport behavior, making it attractive for a variety of electronic and optoelectronic applications. Controlled and efficient synthesis of 1L WSe2 using chemical vapor deposition (CVD) is often challenging because of the high temperatures required to generate a steady flux of tungsten atoms in the vapor phase from the oxide precursors. Here, the use of halide-assisted low-pressure CVD with NaCl helps to reduce the growth temperature to ～750 °C, which is lower than the typical temperatures needed with conventional CVD for realizing 1L WSe2. Moreover, we experimentally probed the quantum multibody interactions in 1L WSe2 ascribed to excitons, trions, and other localized states by analyzing the temperature-dependent photoluminescence spectra, where such multibody interactions govern the intrinsic electronic and optoelectronic properties of 1L WSe2 for device platforms. The role of the metal?2D semiconductor interface is also critical to realize high-performance devices. In this study, a 1L WSe2-based photodetector was fabricated using Al contacts, which shows a high photoresponsivity, and the interface-state density Dit of the Al/WSe2 junction was computed to be the lowest reported to date ～3.45 × 1012 cm?2 eV?1. Our work demonstrates the tremendous potential of WSe2 to open avenues for state-of-the-art electronic, optoelectronic, and quantum-optoelectronic devices using scalable synthesis routes.
关键词： transitional-metal dichalcogenides,photodetector,tungsten diselenide (WSe2),two-dimensional (2D) materials,quantum multibody interactions,interface-state density,chemical vapor deposition (CVD)
更新于2025-09-11 14:15:04
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Direct, transfer-free growth of large-area hexagonal boron nitride films by plasma-enhanced chemical film conversion (PECFC) of printable, solution-processed ammonia borane
摘要： Synthesis of large-area hexagonal boron nitride (h-BN) films for two-dimensional (2D) electronic applications typically requires high temperatures (~1000 oC) and catalytic metal substrates which necessitate transfer. Here, analogous to plasma-enhanced chemical vapor deposition, a non-thermal plasma is employed to create energetic and chemically-reactive states such as atomic hydrogen and convert a molecular precursor film to h-BN at temperatures as low as 500 oC directly on metal-free substrates – a process we term plasma-enhanced chemical film conversion (PECFC). Films containing ammonia borane as a precursor are prepared by a variety of solution processing methods including spray deposition, spin coating, and ink-jet printing, and reacted in a cold-wall reactor with a planar dielectric barrier discharge operated at atmospheric pressure in a background of argon or mixture of argon and hydrogen. Systematic characterization of the converted h-BN films by micro Raman spectroscopy shows that the minimum temperature for nucleation on silicon-based substrates can be lowered from 800 to 500 oC by the addition of a plasma. Furthermore, the crystalline domain size, as reflected by a decrease in the full-width-half-maximum, increased by more than 3 times (>40 cm-1 to ~13 cm-1). To demonstrate the potential of the h-BN films as a gate dielectric in 2D electronic devices, molybdenum disulfide field-effect transistors were fabricated and the field effect mobility was found to be improved by up to four times over silicon dioxide. Overall, PECFC allows h-BN films to be grown at lower temperatures and with improved crystallinity than CVD, directly on substrates suitable for electronic device fabrication.
关键词： two-dimensional (2D) material,plasma,chemical vapor deposition (CVD),boron nitride (BN)
更新于2025-09-11 14:15:04
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The Preparation and Optical Properties of Ni(II) and Mn(II) Doped in ZnTe Nanobelt/Nanorod by Using Chemical Vapor Deposition
摘要： The doping techniques are often used to modify the properties of semiconductors. Transition metal ion doping in semiconductor can lead to dilute magnetic semiconductors (DMSs), which may initiate some novel properties related to spins. In contrast to the wide band semiconductor ZnO, ZnSe and CdS crystal the transition metal (TM) ion aggregate can be the origin of the ferromagnetic behaviors, which influence their optical properties mainly through the exciton-spin interactions due to their high exciton binding energy. For narrow band semiconductor, the carrier-spin coupling is the main cause of magnetism as observed in ZnTe. The ZnTe nanobelt for DMS with the TM ions such as Ni(II) and Mn(II) doping mainly induce the excess carrier effect in the lattice after photo-excitation, whose optical properties are also strongly depended on the fabrication method structure and morphology. Photo-excited carriers and electron–phonon interaction (but less excitons) are responsible for their large redshifts in ZnTe nanostructures. The strong interaction between the doped magnetic ion spins and holes, electron–phonon coupling, p–d hybridization as well as local electron correlation in TM ions determined their optical properties. TM ions incorporation in ZnTe lattice has suppressed the broad defect emission band far from the bandedge and broadened the electron correlations and electron hole plasma band near bandedge when excited by the rising excitation powers. We also identified that the polarized PL of Ni(II) and Mn(II) doped samples to calculate the strain dependence of band splitting near valance band.
关键词： Chemical Vapor Deposition (CVD),Transition Metal Ion,Polarization,Dilute Magnetic Semiconductor (DMS),Luminescence,II–VI Semiconductor
更新于2025-09-09 09:28:46
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Chemical Vapor Deposition Growth of Single Crystalline CoTe <sub/>2</sub> Nanosheets with Tunable Thickness and Electronic Properties
摘要： Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDs) have recently drawn increasing interest for fundamental studies and potential applications in catalysis, charge density wave (CDW), interconnections, spin-torque devices, as well superconductors. Despite some initial efforts, the thickness-tunable synthesis of atomically thin MTMDs remains a considerable challenge. Here we report controlled synthesis of 2D cobalt telluride (CoTe2) nanosheets with tunable thickness using an atmospheric pressure chemical vapor deposition (APCVD) approach and investigate their thickness-dependent electronic properties. The resulting nanosheets show a well-faceted hexagonal or triangular geometry with a lateral dimension up to ～200 μm. Systematic studies of growth at varying growth temperatures or flow rates demonstrate that nanosheets thickness is readily tunable from over 30 nm down to 3.1 nm. X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution scanning transmission electron microscope (STEM) studies reveal the obtained CoTe2 nanosheets are high-quality single crystals in the hexagonal 1T phase. Electrical transport studies show the 2D CoTe2 nanosheets display excellent electrical conductivities up to 4.0 × 105 S m?1 and very high breakdown current densities up to 2.1 × 107 A/cm2, both with strong thickness tunability.
关键词： Two-dimensional (2D),cobalt telluride (CoTe2),electronic properties,chemical vapor deposition (CVD),metallic transition metal dichalcogenides (MTMDs)
更新于2025-09-04 15:30:14