Pressure Chemical Vapor Deposition Method Research Articles

Synthesis and characterization of graphene on copper foil via atmospheric pressure chemical vapor deposition method and its impact on electrical properties

Copper, prized for its exceptional electrical conductivity, thermal conductivity, and mechanical strength, is a staple in electronic applications. The ongoing quest for enhanced performance in miniaturized technologies has led to exploring copper-graphene composites, particularly those integrating bilayer graphene (BLG). This study investigates the enhancement of electrical conductivity in copper through the incorporation of BLG via atmospheric pressure chemical vapor deposition (APCVD). The research highlights the APCVD method's ability to grow high-quality BLG on high-purity oxygen-free copper foil, demonstrating significant improvements in electrical properties. Detailed characterization reveal that the graphene growth process induces structural changes in the copper, promoting ideal crystallographic orientations and larger grain sizes. This process achieves nearly complete graphene coverage and results in a copper/graphene (Cu/GR) composite with minimal defects. The electrical conductivity of the Cu/GR composite significantly increased to 59.32 × 10⁶ S·m⁻1, a 7.83 % improvement over the pristine copper foil. This enhancement is attributed to the increased carrier density and mobility within the composite. These advancements suggest the potential of APCVD-grown graphene for various high-performance electronic applications, providing a promising pathway for further development and optimization of graphene-copper composites.

Mixed phase iron oxides thin layers by atmospheric-pressure chemical vapor deposition method

This paper provides a simple method for producing a metal oxide thin layer methodology by atmospheric pressure chemical vapor deposition (APCVD) synthesis over stainless steel substrates. This methodology enables the formation of thin iron oxide layers at its performance at various temperatures of 330 °C, 430 °C, and 530 °C. The deposition arises from thermal decomposition of the iron organometallic precursor Fe3(CO)12, forming a thin layer of iron oxide is, by the ozone present in the reaction chamber promoting the deposition of the iron oxide particles over the substrate. The Raman characterization suggest that at 330 °C, a mixture of hematite and magnetite is predominant on the as deposited substrates, also hematite modes show to be more pronounced as the band at 300 cm-1 narrows. Conversely, magnetite is prominent at higher synthesis temperatures, exhibiting a more intense Eg5 mode at 680 cm-1. The particles exhibit a uniform morphology, with both metal oxide phases coexisting. The average diameter of the particles is 50 nanometers as scanning electronic microscopy shows in a transversal sample section.•The formation of particles is attributed to the combination of iron ions +2 and +3 in the deposition process and their interaction with oxygen in the given synthesis parameters at atmospheric pressure chemical vapor deposition (APCVD).

Water assisted atmospheric CVD super growth of vertically aligned CNT forest for supercapacitor application

We report a high growth rate (37 μm/min) synthesis of vertically aligned carbon nanotube (VACNT) forest, achieving remarkable height exceeding a millimetre with good crystallinity. VACNTs with few numbers of walls have been grown over Fe–Co/Al2O3/SiO2 coated Si wafer using the water assisted atmospheric pressure chemical vapour deposition (WACVD) method. The key to this success lies in the synergistic combination of a bimetallic catalyst (Fe-Co) with buffer Al2O3 layer and the WACVD method. Notably, the VACNT forest, synthesised at optimized conditions can be directly used without the need for additional post-growth purification processes, eliminating the risk of potential damage to the CNTs. Finally, the VACNT forest exhibits excellent areal capacitance of 133.33 mF/cm2 at a current density of 1 mA/cm2 with outstanding cyclic stability of 130 % @ 3000 cycles.

Direct Growth Graphene Via Atmospheric Pressure Chemical Vapour Deposition

The integration of graphene in field-effect transistor (FET) has aroused tremendous attention in the field of sensor technology, particularly for electronic biosensors. However, transferring graphene from metal substrates has destructive effects on the electrical characteristics of the graphene film, leading to severe impurities and defects. Here, we investigated a new approach of technique to synthesis direct- growth semiconducting graphene via atmospheric pressure chemical vapour deposition (APCVD) method. In this study we observe the effects of different reaction times, carbon concentrations and temperatures on the carbon arrangement in graphene. The synthesised graphene was characterised by Raman spectroscopy and field emission scanning electron microscopy (FESEM) to observe the quality of graphene formation. From the Raman analysis, the I2D/IG ratio < 1 indicates the formation of graphene in multiple layers. The ID /IG ratio < 1 was also observed, indicating that the graphene has less disorder of defects. Based on the electrical measurement of the material at estimated distance of 250 μm, a higher I2D/IG ratio leads to a higher resistance. Full width at half maximum (FWHM) of 2D band shows graphene with the highest I2D/IG ratio has the lowest value of FWHM. As the conclusion, these directly grown semiconducting graphene layers can be efficiently integrated into biosensors without any complex post-treatment process.

The GeSe/SnSe heterojunction photodetector with self-powered characteristics and high infrared response performance

We present a GeSe/SnSe van der Waals heterojunction fabricated using the wet transfer technique. GeSe and SnSe were synthesized via a low-temperature and atmospheric-pressure chemical vapor deposition method. The GeSe/SnSe heterostructure photodetector demonstrates remarkable rectification characteristics, boasting a rectification ratio of 102, along with an exceptionally low dark current, indicating minimal power consumption. Furthermore, it exhibits a broad optical response, spanning from the visible spectrum (450 nm) to the near-infrared (1064 nm). Under 808 nm laser illumination and reverse bias, the device achieves a responsivity of 19.82 A/W, a detectivity of 4.74 × 109 Jones, and an external quantum efficiency of 3048.32%. Notably, the GeSe/SnSe heterojunction photodetector also exhibits self-powered characteristics, with a responsivity of 0.11 mA/W and a detectivity of 5.44 × 106 Jones at zero bias voltage, accompanied by a fast response time of 23/61 ms (rise/fall). These findings underscore the effectiveness of the GeSe/SnSe heterojunction as a strategy for near-infrared photodetectors to simultaneously achieve low power consumption, high photoresponsivity, and self-powered photodetection, which is promising for optoelectronic device applications.

NaCl-assisted chemical vapor deposition growth of MoSe2 and MoSe2/h-BN heterostructure

As a typical two-dimensional (2D) transition metal dichalcogenides (TMDCs), MoSe2 has attracted lots of interest due to its electronic and optical properties in recent years. The controllable synthesis of 2D MoSe2 and its heterostructure is of considerable importance for achieving diverse applications. Herein, we realized the controlled growth of MoSe2 by atmospheric pressure chemical vapor deposition (APCVD) method through using NaCl as the promoter. Raman and photoluminescence (PL) spectroscopy have been used to investigate the optical properties of MoSe2 domains with different layers. The dependence of structures on synthetic parameter is systematically investigated by tuning the growth conditions. On this basis, the monolayer MoSe2 was constructed on CVD-grown hexagonal boron nitride (h-BN) by an all-CVD approach. Detailed characterizations indicate that MoSe2 deposited on h-BN exhibits improved optical properties as compared to those on SiO2/Si. Our results could enrich the understanding for growth of TMDCs, advocating further investigation of their intrinsic properties and a variety of device applications.

Niobium doping of CVD-WS2 monolayers using solid precursors with and without salt-KBr as a catalyst: A comparative study

The in situ doping of tungsten disulfide (WS2) monolayers with Niobium (Nb) atoms was obtained through the atmospheric pressure chemical vapor deposition (APCVD) method by controlling the Nb2O5 and WO3 precursors mass ratios. Samples were prepared employing the same growth parameters with and without the use of KBr salt as a catalyst. In both cases, the Nb incorporation quenches the luminescence intensity of the doped samples, and it depends on the Nb2O5:WO3 mass ratio. X-ray photoelectron spectroscopy (XPS) measurements were performed, and the observed redshift at the Fermi level indicated p-type doping. Nb-doped WS2 monolayers synthesized without the use of the catalyst have lower defect density, as revealed by a careful Raman analysis, and are free of agglomerates on their monolayers’ basal plane. The use of KBr as the catalyst increases the average crystal size but also increases the disorder effects compared with samples prepared without the use of salt. The presence of agglomerates of impurities at the surface of doped samples was observed in samples prepared with the use of salt as a catalyst. The controlled synthesis of p-type WS2 with low defect density is essential for developing electronic and photonic devices based on WS2 material.

Orietation-controlled synthesis and Raman study of 2D SnTe

Tin telluride (SnTe), as a narrow bandgap semiconductor material, has great potential for developing photodetectors with wide spectra and ultra-fast response. At the same time, it is also an important topological crystal insulator material, with different topological surface states on several common surfaces. Here, we introduce different Sn sources and control the growth of regular SnTe nanosheets along the (100) and (111) planes through the atmospheric pressure chemical vapor deposition method. It has been proven through various characterizations that the synthesized SnTe is a high-quality single crystal. In addition, the angular resolved Raman spectra of SnTe nanosheets grown on different crystal planes are first demonstrated. The experimental results showed that square SnTe nanosheets grown along the (100) plane exhibit in-plane anisotropy. At the same time, we use micro-nanofabrication technology to manufacture SnTe-based field effect transistors and photodetectors to explore their electrical and optoelectronic properties. It has been confirmed that transistors based on grown SnTe nanosheets exhibit p-type semiconductor characteristics and have a high response to infrared light. This work provides a new approach for the controllable synthesis of SnTe and adds new content to the research of SnTe-based infrared detectors.

Development of improved technology for producing graphene-like coating by LPCVD method

The object of research in this work was the coating of oxygraphene on a silicon single crystal substrate. In the work, the LPСVD (Low Pressure Chemical Vapor Deposition) method of deposition from the gas phase at low pressure is used to obtain graphene-like coatings on heat-resistant materials. A feature of the proposed LPCVD method in comparison with the classical method of deposition from the gas phase CVD (Chemical Vapor Deposition) by the method of catalytic decomposition of carbon-containing gas followed by the deposition of a graphene-like coating on a copper template is the use of a higher partial gas pressure, which leads to the deposition of graphene-like waste not only on the surface of the copper template-catalyst, but also in the entire volume of the reaction chamber and the materials introduced into it. A monocrystalline silicon template was used as a model for coating. The resulting coatings of different thicknesses were examined by scanning electron microscopy, Raman spectroscopy, and density was assessed by helium pycnometry. Based on the analysis of the results obtained using the method of scanning electron microscopy, the possibility of varying the thickness of the oxygraphene coating was shown. In addition, the formation of oxygraphene on a silicon single crystal substrate was confirmed by the Raman spectroscopy method, namely the presence of characteristic peaks in the spectra of the studied materials. Using the helium pycnometry method, a decrease in the density of the coated material from 2.25 g/cm3 to 2.08 g/cm3 was found. It was established that the greater the coating thickness, the lower the density. The general analysis showed that the developed LPСVD technology allows obtaining an oxygraphene coating on materials of any shape, porosity, size and resistant to temperatures above 600 °С in order to functionalize their surface and improve and improve their properties.

Vertically molybdenum disulfide nanosheets on carbon cloth using CVD by controlling growth atmosphere for electrocatalysis

Molybdenum disulfide (MoS2) has been deemed as one of the promising noble-metal-free electrocatalysts for hydrogen evolution reaction (HER), but it suffers from the inert basal plane and low electronic conductivity. Regulating the morphology of MoS2 during the synthesis on conductive substrates is a synergistic strategy for enhancing the HER performance. In this work, vertical MoS2 nanosheets were fabricated on carbon cloth (CC) using an atmospheric pressure chemical vapor deposition method. The growth process could be effectively tuned through introducing hydrogen gas during vapor deposition process, resulting in nanosheets with increased edge density. The mechanism for edge-enriching through controlling the growth atmosphere is systematically studied. The as-prepared MoS2 exhibits excellent HER activity due to the combination of optimized microstructures and coupling with CC. Our findings provide new insights to design advanced MoS2-based electrocatalysts for HER.

Sub-500 nm patterned synthesis of corrosion resistant SnO2 and Pt@SnO2 using metal-organic precursor

In this study, a thin film of transparent conducting metal oxide, SnO2, is obtained using a novel metal-organic precursor, Sn-TOABr complex. The precursor is synthesized by phase-transferring tin from the aqueous layer to the liquid-liquid interface. The formed precursor is used for depositing SnO2 thin films over arbitrary and even large substrates via the modified atmospheric pressure chemical vapor deposition (MAPCVD) method in a simple furnace at 450 °C. The vapor-deposited SnO2 thin films are crystalline, semiconducting, highly transparent with excellent mechanical robustness against scratch and scotch tape tests, and resistant towards corrosive media. The obtained robust thin films via this MAPCVD technology expand applications towards protective coatings for arbitrary substrates. Using a simple direct micromolding technique, sub-500 nm patterns of SnO2 and Pt@SnO2 were obtained. This single-step soft lithography patterning technique, besides being cost-effective, offers a large throughput.

Effect of substrate temperature on the morphology of chemical vapor deposition grown two-dimensional metallic vanadium diselenide

Two-dimensional (2D) metallic transition metal dichalcogenides (TMDs) have emerged as a promising class of materials for engineering novel electronic phases, 2D magnetism, superconductivity, and unique electronic applications. Vanadium dichalcogenides, in particular, exhibit a wide range of unusual physical and chemical properties, making them suitable for novel applications in condensed matter physics, materials science, and device physics. Here, we investigate the effect of substrate temperature on the morphology of 2D vanadium diselenide (VSe2) nanosheets synthesized by the atmospheric pressure chemical vapor deposition (APCVD) method. The growth is carried out on SiO2/Si, fluorphlogopite mica [KMg3(AlSi3O10)F2], and h-BN/SiO2/Si substrates. Our findings reveal that continuous thick VSe2 films are obtained at a substrate temperature of 650 °C, while large-sized VSe2 nanosheets with lower thickness are formed at intermediate substrate temperatures of 550–500 °C. This study provides insights into the substrate temperature-controlled growth of 2D VSe2 nanosheets for various potential applications.

Multilayer SnS2/few-layer MoS2 heterojunctions with in-situ floating photogate toward high-performance photodetectors and optical imaging application

Since the successful preparation of the monolayer MoS2 phototransistor, two-dimensional (2D) layered materials (2DLMs) have been regarded as one of the most compelling candidates toward the implementation of the next generation of novel optoelectronic devices and systems. However, most reported 2DLM photodetectors suffer from specific shortcomings, such as low responsivity, large dark current, low specific detectivity, low on/off ratio, and sluggish response rate. Herein, multilayer SnS2/few-layer MoS2 van der Waals heterostructures have been constructed by stacking the MoS2 and SnS2 nanosheets grown by a single atmospheric pressure chemical vapor deposition method. The SnS2/MoS2 heterojunction photodetector demonstrates competitive overall performance with a large on/off ratio of 171, a high responsivity of 28.3 A W−1, and an excellent detectivity of 1.2 × 1013 Jones. In addition, an ultrafast response rate with the response/recovery time down to 1.38 ms/600 is achieved. The excellent properties are associated with the synergy of type-II band alignment of SnS2/MoS2 and the in-situ formed seamless floating photogate, which contribute to separating the photoexcited electron-hole pairs and extending the carrier lifetime. Taking advantage of the excellent photosensitivity, the SnS2/MoS2 device demonstrates proof-of-concept optical imaging application. On the whole, this study provides a distinctive perspective to implement advanced photodetectors with competitive overall performance.

Optimized APCVD method for synthesis of monolayer H-Phase VS2 crystals

Abstract Monolayer transition metal dichalcogenides, specifically H-phase vanadium disulfide (VS2), hold great significance as fundamental components for next-generation low-dimensional spintronic, optoelectronic, and future electronic devices. They also offer an opportunity to explore the intrinsic magnetic properties associated with monolayer H-phase VS2 crystals at room temperature. However, there have been limited experimental studies on synthesizing pure monolayer H-phase VS2 crystals using sodium metavanadate (NaVO3) and sulfur (S) as precursors for vanadium (V) and S, respectively. In this study, we present a facile atmospheric pressure chemical vapor deposition (APCVD) approach for the synthesizing monolayer H-phase VS2 crystals with a thickness of ∼0.7 nm. The lateral dimensions of monolayer VS2 crystals extends up to ∼26 µm. Additionally, we have modulated the growth parameters, such as the temperature of NaVO3 and the Ar gas flow rate, to obtain VS2 flakes with different sizes and morphologies. This significant advancement paves the way for the synthesis of monolayer H-phase VS2 crystals on SiO2/Si substrates using the APCVD technique.

Boron-carbon-silicon film chemical vapor deposition by boron trichloride, dichlorosilane and monomethylsilane gases

A boron-carbon-silicon film was formed by an atmospheric pressure chemical vapor deposition method using a gas mixture of boron trichloride, dichlorosilane and monomethylsilane in ambient hydrogen at 800–1000 °C. The boron, carbon and silicon concentrations in the obtained film were about 15–30 %, 0–10 % and 50–80 %, respectively. With the increasing monomethylsilane gas flow rate, the carbon and silicon concentrations in the obtained film increased and decreased, respectively. In the obtained film, various chemical bonds between the boron, carbon and silicon existed, except for the carboncarbon bond. The following conclusions were obtained. (i) The carbon atoms existing at the surface have a chemical bond with the boron atoms, but not with the carbon and silicon atoms. (ii) The surface intermediate compound of boron chloride helps incorporating the carbon, while that of dichlorosilane does not. (iii) The etching by the hydrogen chloride gas significantly influenced the film formation process at higher than 900 °C.

Hexagonal Single-Crystal CoS Nanosheets: Controllable Synthesis and Tunable Oxygen Evolution Performance.

Cobalt-based sulfides with variable valence states and unique physical and chemical properties have shown great potential as oxygen evolution reaction (OER) catalysts for electrochemical water-splitting reactions. However, poor morphological characteristics and a small specific surface area limit its further application. Here, hexagonal single-crystal two-dimensional (2D) CoS nanosheets with different thicknesses are successfully prepared by an atmospheric-pressure chemical vapor deposition method. Because of the advantages of the 2D structure, more exposed catalytic active sites, better reactant adsorption ability, accelerated electron transfer, and enhanced electrical conductivities can be achieved from the thinnest 5 nm CoS nanosheets (CoS-5), significantly improving OER performance. The electrochemical tests manifest that CoS-5 show an overpotential of 290 mV at 10 mA cm-2 and a Tafel slope of 65.6 mV dec-1 in the OER in an alkaline solution, superior to those for other thicknesses of CoS, bulk CoS, and RuO2. For the mechanistic investigation, the lowest charge transfer resistance (Rct) and the highest double-layer capacitance (Cdl) were obtained for CoS-5, demonstrating the faster OER kinetics and the larger active area. Density functional theory calculations further reveal the enhanced density of states around the Fermi level and higher H2O molecule adsorption energy for thinner CoS nanosheets, promoting its intrinsic catalytic activity. Moreover, the two-electrode system with CoS-5 as the anode and Pt/C as the cathode requires only 1.56 V to attain 10 mA cm-2 in the overall water-splitting reaction. We believe that this study will provide a fresh view for thickness-dependent catalytic performance and offers a new material for the study of electronic and energy devices.

Tunable hierarchical hexagonal nickel telluride (Ni3Te2) laminated microsheets as flexible counter electrodes for high-performance fibrous dye-sensitized solar cells: Accelerated electrocatalysis reduction of I3− ions

To develop highly active catalysts as counter electrodes is another promising way for improving the photovoltaic conversion efficiency (PCE) of fibrous dye-sensitized solar cells (FDSSCs). Then considering their applications in wearable electronic system, the designed fibrous counter electrodes (FCEs) should possess a good mechanical flexibility except high catalysis performances. Here in this work, hexagonal nickel telluride (Ni3Te2) microsheets with tunable diameters and thicknesses were in-situ prepared via an atmospheric pressure chemical vapor deposition method on nickel wires. Benefiting from their two-dimensional laminated structure and asymmetric crystalline structure, the Ni3Te2 microsheets show a high catalytic activity for the reduction of I3- → I- during the photoelectrochemical processes in FDSSCs. And cell tests show that the maximum PCE of FDSSCs with Ni3Te2 FCEs reaches 11.81% (with an average value of 10.47%), which is 2.10 times that of the ones with Pt FCEs (5.62%). Furthermore, series of optimization on the microscale morphologies of Ni3Te2 microsheets indicates that the suitable diameter (30 ∼ 40 μm) and thickness (ca. 3.0 μm) are suitable for the diffusion and reduction of I3- ions. Besides, the FDDSCs with Ni3Te2 PCEs show a high cycling stability and an excellent dynamic bending stability (attenuation rate of 0.12‰ per bending cycle). This research would provide some insights into the design of high-performance FCEs for FDSSCs towards wearable electronic devices.

Growth, Raman Scattering Investigation and Photodetector Properties of 2D SnP.

As an important metal phosphides material, 2D tin phosphides (SnPx 0< x≤3) have been theoretically predicted to have intriguing physicochemical properties and potential applications in electronics, optoelectronics, and energy fields. However, the synthesis of high-quality 2D SnP single crystal has not been reported due to the lack of efficiency and reliable growth method. Here, a facile atmospheric pressure chemical vapor deposition (APCVD) method is developed to realize the growth of high-quality 2D SnP nanosheets, by employing tin (Sn) foil as both liquid metal substrates and reaction precursor. Temperature-dependent and angle-resolved polarization Raman spectra observed Raman peaks located at 142.6, 303.3, and 444.2 cm-1 are concluded to belong to A1g mode, which are consistent with the theoretical calculation results. Moreover, the field-effect transistor (FET) devices based on SnP nanosheets show a typical n-type characteristic with an on/off ratio of 103 at 200 K. SnP nanosheets also demonstrate excellent photoresponse performance under the illumination of 473, 532, and 639nm lasers, which can be tuned by Vgs , Vds , and light power density. It is believed that these findings can provide the first-hand experimental information for the future study of 2D SnP nanosheets.

Near‐Infrared Electroluminescent Light‐Emitting Transistors Based on CVD‐Synthesized Ambipolar ReSe2 Nanosheets

AbstractNear‐infrared light‐emitting technology is ideal for noncontact diagnostic medical imaging and high‐speed data communications. High‐quality ReSe2 nanosheets of anisotropic single‐crystal structure with a bandgap of 1.26 eV (≈984 nm) are synthesized with an atmospheric pressure chemical vapor deposition (APCVD) method. The as‐synthesized ReSe2 nanosheets‐fabricated light‐emitting transistors (LETs) exhibit nearly symmetric ambipolar characteristics in electrical transport. Judicious selection of asymmetric platinum (Pt)/chromium (Cr) electrodes, with their work functions matching respectively the conduction‐ and valence‐band edges of ambipolar ReSe2, generates a low turn‐on voltage ReSe2‐LET with the balanced number density and field‐effect mobility of bipolar carriers (i.e., electrons and holes). Room‐temperature near‐infrared electroluminescence (NIR EL) from the frequency‐modulated ReSe2‐LET has been observed unprecedentedly with the assistance of a lock‐in detection system. The NIR EL intensity is tested by varying the bias voltage applied to the ReSe2‐LET devices with different channel lengths. The wavelength of the NIR EL from ReSe2‐LET is differentiated with optical bandpass filters. Room‐temperature angle‐dependent two lobe‐shaped EL pattern manifests the inherent anisotropic in‐plane excitonic polarization of the ReSe2 crystal. The highly stable NIR EL from ReSe2‐LETs provides prospective 2D material‐based ultrathin scalable data communication electronics for future development.

Water-assisted controllable growth of atomically thin WTe2 nanoflakes by chemical vapor deposition based on precursor design and substrate engineering strategies

WTe2 nanostructures have intrigued much attention due to their unique properties, such as large non-saturating magnetoresistance, quantum spin Hall effect and topological surface state. However, the controllable growth of large-area atomically thin WTe2 nanostructures remains a significant challenge. In the present work, we demonstrate the controllable synthesis of 1T′ atomically thin WTe2 nanoflakes (NFs) by water-assisted ambient pressure chemical vapor deposition method based on precursor design and substrate engineering strategies. The introduction of water during the growth process can generate a new synthesized route by reacting with WO3 to form intermediate volatile metal oxyhydroxide. Using WO3 foil as the growth precursor can drastically enhance the uniformity of as-prepared large-area 1T′ WTe2 NFs compared to WO3 powders. Moreover, highly oriented WTe2 NFs with distinct orientations can be obtained by using a-plane and c-plane sapphire substrates, respectively. Corresponding precursor design and substrate engineering strategies are expected to be applicable to other low dimensional transition metal dichalcogenides, which are crucial for the design of novel electronic and optoelectronic devices.