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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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Two-dimensional (PEA) <sub/>2</sub> PbBr <sub/>4</sub> perovskite single crystals for a high performance UV-detector
摘要： Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDCs), the complement of 2D semiconducting TMDCs, have attracted extensive attentions in recent years because of their versatile properties such as superconductivity, charge density wave, and magnetism. To promote the investigations of their fantastic properties and broad applications, the preparation of large-area, high-quality, and thickness-tunable 2D MTMDCs has become a very urgent topic and great efforts have been made. This topical review therefore focuses on the introduction of the recent achievements for the controllable syntheses of 2D MTMDCs (VS2, VSe2, TaS2, TaSe2, NbS2, NbSe2, etc.). To begin with, some earlier developed routes such as chemical vapor transport, mechanical/chemical exfoliation, as well as molecular beam epitaxy methods are briefly introduced. Secondly, the scalable chemical vapor deposition methods involved with two sorts of metal-based feedstocks, including transition metal chlorides and transition metal oxidations mixed with alkali halides, are discussed separately. Finally, challenges for the syntheses of high-quality 2D MTMDCs are discussed and the future research directions in the related fields are proposed.
关键词： metallic transition metal dichalcogenides,synthesis,chemical vapor deposition,two dimensional
更新于2025-09-19 17:15:36
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GaN grown by metalorganic vapor phase epitaxy
摘要： We report on residual impurities in semi-polar (3031) and (2021) GaN homo-epitaxial layer grown by metal-organic chemical vapor deposition. The (3031) and (2021) GaN layer showed atomically smooth surface and clear steps toward [0001] and [000-1], respectively. The residual impurity concentrations of oxygen and carbon were below the detection limit of secondary-ion mass spectroscopy. Low-temperature photoluminescence revealed that (2021) GaN layer consisted free excitons and Si donor bound excitons, along with two-electron satellite lines and longitudinal optical (LO) phonon coupling transitions. The results indicate semi-polar (3031) and (2021) GaN epitaxial layers are promising candidates in obtaining a high quality GaN drift layer for vertical GaN devices.
关键词： B2. Semiconducting III-V materials,A3. Metalorganic chemical vapor deposition,B1. Nitrides,A1. Crystal structure,A1. Impurities
更新于2025-09-19 17:15:36
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Phosphorous Catalytic‐Doping of Silicon Alloys for the Use in Silicon Heterojunction Solar Cells
摘要： Herein, the effectiveness of post-deposition catalytic-doping (cat-doping) on various doped silicon alloys, i.e., microcrystalline silicon (μc-Si:H), nanocrystalline silicon oxide (nc-SiOx:H), and microcrystalline silicon carbide (μc-SiC:H), for the use in silicon heterojunction solar cells is investigated. Phosphorous (P) pro?les by secondary ion mass spectrometry (SIMS) reveal the P distribution and its difference in these three silicon alloy ?lms. Conductivity and effective charge carrier lifetime of different samples are found to increase to different extents after cat-doping process. Coexistence of thermal annealing, hydrogenation, and phosphorus doping is con?rmed by using different gases during the cat-doping process.
关键词： silicon alloy,post-depositions,silicon heterojunction solar cells,hot-wire chemical vapor depositions,catalytic chemical vapor deposition
更新于2025-09-19 17:13:59
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Showerhead-Assisted Chemical Vapor Deposition of Perovskite Films for Solar Cell Application
摘要： In the last years, perovskite solar cells have attracted great interest in photovoltaic (PV) research due to their possibility to become a highly efficient and low-cost alternative to silicon solar cells. Cells based on the widely used Pb-containing perovskites have reached power conversion efficiencies (PCE) of more than 20 %. One of the major hurdles for the rapid commercialization of perovskite photovoltaics is the lack of deposition tools and processes for large areas. Chemical vapor deposition (CVD) is an appealing technique because it is scalable and furthermore features superior process control and reproducibility in depositing high-purity films. In this work, we present a novel showerhead-based CVD tool to fabricate perovskite films by simultaneous delivery of precursors from the gas phase. We highlight the control of the perovskite film composition and properties by adjusting the individual precursor deposition rates. Providing the optimal supply of precursors results in stoichiometric perovskite films without any detectable residues.
关键词： precursor deposition rates,stoichiometric perovskite films,showerhead-based CVD,chemical vapor deposition,perovskite solar cells
更新于2025-09-19 17:13:59
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Thickness-controlled synthesis of CoX2 (X = S, Se, Te) single crystalline 2D layers with linear magnetoresistance and high conductivity.
摘要： Two-dimensional (2D) materials especially transition metal dichalcogenides (TMDs) have drawn intensive interests owing to their plentiful properties. Some TMDs with magnetic elements (Fe, Co, Ni, etc.) are reported to be magnetic theoretically and experimentally, which undoubtedly provide a promising platform to design functional devices and study physical mechanisms. Nevertheless, plenty of the theoretical TMDs remain unrealized experimentally. In addition, the governable synthesis of these kinds of TMDs with desired thickness and high crystallinity poses a tricky challenge. Here, we report a controlled preparation of CoX2 (X = S, Se, Te) nanosheets through chemical vapor deposition (CVD). The thickness, lateral scale and shape of the crystals show great dependence with temperature and the thickness can be controlled from monolayer to tens of nanometers. Magneto-transport characterization and Density Function Theory (DFT) simulation indicate CoSe2 and CoTe2 are metallic. Besides, unsaturated and linear magnetoresistance have been observed even up to 9 Tesla. The conductivity of CoSe2 and CoTe2 can reach 5 × 106 and 1.8 × 106 S/m respectively, which is pretty high and even comparable with silver. These cobalt-based TMDs show great potential to work as 2D conductors and also provide a promising platform for investigating their magnetic properties.
关键词： Transition metal dichalcogenides,Magnetoresistance,Conductivity,Two-dimensional materials,Chemical vapor deposition
更新于2025-09-19 17:13:59
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Metal-Semiconductor-Metal ?μ-Ga2O3 Solar-Blind Photodetectors with a Record High Responsivity Rejection Ratio and Their Gain Mechanism
摘要： In recent years, Ga2O3 solar-blind photodetector (SBPD) has been attached great attention for its potential application in solar-blind imaging, deep space exploration, and confidential space communication, etc. In this work, we demonstrated an ultrahigh performance ε-Ga2O3 metal-semiconductor-metal (MSM) SBPD. The fabricated photodetectors exhibited record-high responsivity and fast decay time of 230 A/W and 24 ms, respectively, compared with MSM-structured Ga2O3 photodetectors reported to date. Additionally, the ε-Ga2O3 MSM SBPD presents ultrahigh detectivity of 1.2×1015 Jones with low dark current of 23.5 pA under the operation voltage of 6 V, suggesting its strong capability of detecting an ultraweak signal. The high sensitivity and wavelength selectivity of the photodetector were further confirmed by the record high responsivity rejection ratio (R250nm/R400nm) of 1.2×105. From the temperature-dependent electrical characteristics in the dark, the thermionic field emission and Poole-Frenkel emission were found to be responsible for the current transport in the low and high electric field regimes, respectively. In addition, the gain mechanism was revealed by the Schottky barrier lowering effect due to the defect states at the interface of metal contact and Ga2O3 or in the bulk of Ga2O3 based on current transport mechanism and density functional theory (DFT) calculation. These results facilitate a better understanding of ε-Ga2O3 photoelectronic devices and provide possible guidance for promoting their performance in future solar-blind detection applications.
关键词： rejection ratio,metal-organic chemical vapor deposition,ε-Ga2O3,responsivity,high-performance,solar-blind photodetector
更新于2025-09-19 17:13:59
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Plasmonic gold sensitization of ZnO nanowires for solar water splitting
摘要： This paper reports the synthesis of plasmonic gold sensitized ZnO nanowires by chemical vapor deposition and subsequent photoreduction method. The well sensitization of Au nanoparticles with mean diameter of 5.3 nm on ZnO nanowires yield a higher photocurrent density of 1.06 mAcm-2 under illumination. Accordingly, Au nanoparticles on ZnO nanowires reveals the maximum photoelectrochemical water splitting efficiency of 0.45% at + 0.8 VRHE, which is higher than the ZnO nanowires (0.22% at + 0.8 VRHE). The enhanced photocurrent density and efficiency is due to the effective charge separation and transportation originating from metal support interaction, 1D nanostructure as well as surface plasmon resonance effect of Au nanoparticles.
关键词： Interfaces,Photoelectrochemical water splitting,Chemical vapor deposition,ZnO nanowires,Au nanoparticles
更新于2025-09-19 17:13:59
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Composition, structure and morphology of ZnOa??Co3O4 ceramic targets in the process of pulsed laser thin film deposition
摘要： This paper presents the results of the study of the composition, structure and morphology of ZnO–Co3O4 ceramic targets before and after laser ablation by the KrF excimer laser. X-ray diffraction analysis showed that the composition of the targets changes under the thermal effects of laser radiation: a new phase of CoO of the cubic structure is formed (a = 4.25 ?). The radial distribution of elements in the ZnO–Co3O4 targets after ablation by the KrF excimer laser was discovered for the first time. The atomic concentration of cobalt in the center was determined to be several times higher than its concentration at the edge of the targets. This can be explained by the thermal model of laser-semiconductor interaction. The morphology of the targets surface after the laser ablation was discovered to undergo significant changes. Pulsed nanosecond laser radiation induces the formation of center-oriented cone-shaped structures and micro-whiskers on the target surface. It was determined that the higher is the concentration of doping impurities in the target, the greater is the number of structures observed on the surface. The formation of “cones” and microwhiskers is explained by the generalized growth model of the vapor–liquid–crystal mechanism.
关键词： A1. Growth models,A2. Bulk crystal growth,A1. Characterization,A3. Physical vapor deposition processes,B2. Semiconducting II-VI materials,A1. Crystal structure
更新于2025-09-19 17:13:59
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Nucleation and growth dynamics of graphene grown through low power capacitive coupled radio frequency plasma enhanced chemical vapor deposition
摘要： We present the study on graphene growth on Cu substrate through low power capacitive coupled radio frequency (RF) plasma enhanced chemical vapor deposition. Fully-covered graphene was grown on Cu substrate through a plasma composed of various argon/methane/hydrogen gas ratio with a 50 W RF power source within a minute under a relatively low substrate temperature at 850 +C. The nucleation and growth dynamics is further investigated through processing and analysis of the images acquired through scanning electron microscopy, and interpreted with a modi?ed Johnson-Mehl-Avrami-Kolmogorov model. The roles of hydrogen in limiting the nucleation density and stabilization of the graphene grain edges are discussed in light of the analysis, and a time dependent grain expansion rate in which the graphene grains grow fast at the early stage and saturated at later stage is implemented into the model to achieve good ?tting of the coverage evolution.
关键词： Johnson-Mehl-Avrami-Kolmogorov model,Plasma enhanced chemical vapor deposition,Growth dynamics,Graphene,Nucleation
更新于2025-09-19 17:13:59