Showing papers on "Chemical vapor deposition published in 2016"
TL;DR: It is shown that single-crystal graphene can be grown on copper foils with a growth rate of 60 μm-1, and single- Crystal graphene domains with a lateral size of 0.3 mm are able to be grown with just 5 s.
Abstract: Single-crystal graphene can be grown on a copper foil at a rate of 60 μm s-1 by using an adjacent oxide substrate that continuously supplies oxygen to the surface of the copper catalyst. Graphene has a range of unique physical properties1,2 and could be of use in the development of a variety of electronic, photonic and photovoltaic devices3,4,5. For most applications, large-area high-quality graphene films are required and chemical vapour deposition (CVD) synthesis of graphene on copper surfaces has been of particular interest due to its simplicity and cost effectiveness6,7,8,9,10,11,12,13,14,15. However, the rates of growth for graphene by CVD on copper are less than 0.4 μm s–1, and therefore the synthesis of large, single-crystal graphene domains takes at least a few hours. Here, we show that single-crystal graphene can be grown on copper foils with a growth rate of 60 μm s–1. Our high growth rate is achieved by placing the copper foil above an oxide substrate with a gap of ∼15 μm between them. The oxide substrate provides a continuous supply of oxygen to the surface of the copper catalyst during the CVD growth, which significantly lowers the energy barrier to the decomposition of the carbon feedstock and increases the growth rate. With this approach, we are able to grow single-crystal graphene domains with a lateral size of 0.3 mm in just 5 s.
329 citations
TL;DR: Temperature-dependent measurements prove that ballistic transport is maintained exceeding 1 μm up to 200 K and the ballistic nature of charge transport is probed by measuring the bend resistance in cross- and square-shaped devices.
Abstract: We report on ballistic transport over more than 28 μm in graphene grown by chemical vapor deposition (CVD) that is fully encapsulated in hexagonal boron nitride. The structures are fabricated by an advanced dry van-der-Waals transfer method and exhibit carrier mobilities of up to three million cm2/(Vs). The ballistic nature of charge transport is probed by measuring the bend resistance in cross- and square-shaped devices. Temperature-dependent measurements furthermore prove that ballistic transport is maintained exceeding 1 μm up to 200 K.
287 citations
TL;DR: The focus here is on the progress of graphene synthesis on Cu foils by CVD, including various CVD techniques, graphene growth mechanisms and kinetics, strategies for synthesizing large-area graphene single crystals, graphene transfer techniques, and, finally, challenges and prospects are discussed.
Abstract: Over the past decade, graphene has advanced rapidly as one of the most promising materials changing human life. Development of production-worthy synthetic methodologies for the preparation of various types of graphene forms the basis for its investigation and applications. Graphene can be used in the forms of either microflake powders or large-area thin films. Graphene powders are prepared by the exfoliation of graphite or the reduction of graphene oxide, while graphene films are prepared predominantly by chemical vapor deposition (CVD) on a variety of substrates. Both metal and dielectric substrates have been explored; while dielectric substrates are preferred over any other substrate, much higher quality graphene large-area films have been grown on metal substrates such as Cu. The focus here is on the progress of graphene synthesis on Cu foils by CVD, including various CVD techniques, graphene growth mechanisms and kinetics, strategies for synthesizing large-area graphene single crystals, graphene transfer techniques, and, finally, challenges and prospects are discussed.
263 citations
Columbia University1, Rice University2, University of Texas at Austin3, Sandia National Laboratories4, Sungkyunkwan University5, University of Central Florida6, Hong Kong University of Science and Technology7, Harvard University8, Texas Instruments9, Ulsan National Institute of Science and Technology10
TL;DR: This work demonstrates that in an oxygen-activated chemical vapour deposition (CVD) process, half-millimetre size, Bernal-stacked BLG single crystals can be synthesized on Cu and discovers new microscopic steps governing the growth of the 2nd graphene layer below the 1st layer.
Abstract: Large, bilayer graphene single crystals can be grown by oxygen-activated chemical vapour deposition. Bernal (AB)-stacked bilayer graphene (BLG) is a semiconductor whose bandgap can be tuned by a transverse electric field, making it a unique material for a number of electronic and photonic devices1,2,3. A scalable approach to synthesize high-quality BLG is therefore critical, which requires minimal crystalline defects in both graphene layers4,5 and maximal area of Bernal stacking, which is necessary for bandgap tunability6. Here we demonstrate that in an oxygen-activated chemical vapour deposition (CVD) process, half-millimetre size, Bernal-stacked BLG single crystals can be synthesized on Cu. Besides the traditional ‘surface-limited’ growth mechanism for SLG (1st layer), we discovered new microscopic steps governing the growth of the 2nd graphene layer below the 1st layer as the diffusion of carbon atoms through the Cu bulk after complete dehydrogenation of hydrocarbon molecules on the Cu surface, which does not occur in the absence of oxygen. Moreover, we found that the efficient diffusion of the carbon atoms present at the interface between Cu and the 1st graphene layer further facilitates growth of large domains of the 2nd layer. The CVD BLG has superior electrical quality, with a device on/off ratio greater than 104, and a tunable bandgap up to ∼100 meV at a displacement field of 0.9 V nm−1.
259 citations
TL;DR: The approach of incorporating graphene electrodes in lateral TMD based devices provides insights on the contact engineering in 2D optoelectronics, which is crucial for the development of high performing ultrathin photodetector arrays for versatile applications.
Abstract: In this report, graphene (Gr) is used as a 2D electrode and monolayer WS2 as the active semiconductor in ultrathin photodetector devices. All of the 2D materials are grown by chemical vapor deposition (CVD) and thus pose as a viable route to scalability. The monolayer thickness of both electrode and semiconductor gives these photodetectors ∼2 nm thickness. We show that graphene is different to conventional metal (Au) electrodes due to the finite density of states from the Dirac cones of the valence and conduction bands, which enables the photoresponsivity to be modulated by electrostatic gating and light input control. We demonstrate lateral Gr–WS2–Gr photodetectors with photoresponsivities reaching 3.5 A/W under illumination power densities of 2.5 × 107 mW/cm2. The performance of monolayer WS2 is compared to bilayer WS2 in photodetectors and we show that increased photoresponsivity is achieved in the thicker bilayer WS2 crystals due to increased optical absorption. This approach of incorporating graphene...
249 citations
TL;DR: An in situ chemical vapor deposition type approach is presented that demonstrates progress towards growth of large area 2D BP with average areas >3 μm2 and thicknesses representing samples around four layers and thicker samples withAverage areas >100 μm 2.
Abstract: Phosphorene, a novel 2D material isolated from bulk black phosphorus (BP), is an intrinsic p-type material with a variable bandgap for a variety of applications. However, these applications are limited by the inability to isolate large films of phosphorene. Here we present an in situ chemical vapor deposition type approach that demonstrates progress towards growth of large area 2D BP with average areas >3 μm2 and thicknesses representing samples around four layers and thicker samples with average areas >100 μm2. Transmission electron microscopy and Raman spectroscopy have confirmed successful growth of 2D BP from red phosphorus.
248 citations
TL;DR: In this paper, a robust, multifunctional, robust, layered VO2/SiO2/TiO2 films were quickly deposited on glass substrates using atmospheric-pressure chemical vapor deposition and fully characterized using structural, vibrational spectroscopy, and electron microscopy techniques.
Abstract: Monoclinic vanadium(IV) oxide (VO2) has received much attention for applications as intelligent solar control coatings, with the potential to reduce the need for both heating and air conditioning loads within building infrastructure. Chemical vapor deposition, a high-throughput industrially scalable method, is an ideal technology for the deposition of VO2 thin films on window panels. However, these films suffer from poor adhesion and are chemically susceptible to attack. In addition, the VO2 films with optimum solar modulation are unfortunately translucent, restraining their commercial use in energy-efficient fenestration. In this work, multifunctional, robust, layered VO2/SiO2/TiO2 films were quickly deposited on glass substrates using atmospheric-pressure chemical vapor deposition and fully characterized using structural, vibrational spectroscopy, and electron microscopy techniques. The VO2/SiO2/TiO2 thin films were designed to exhibit excellent solar modulation properties as well as high transparency a...
216 citations
TL;DR: In this paper, the recent progress of OHP thin-film fabrication based on vapor-based deposition techniques is reviewed and the instrumentation and specific features of each vaporbased method as well as its corresponding device performance.
Abstract: Organometal halide perovskites (OHPs) are currently under the spotlight as promising materials for new generation low-cost, high-efficiency solar cell technology. Within a few years of intensive research, the solar energy-to-electricity power conversion efficiency (PCE) based on OHP materials has rapidly increased to a level that is on par with that of even the best crystalline silicon solar cells. However, there is plenty of room for further improvements. In particular, the development of protocols to make such a technology applicable to industry is of paramount importance. Vapor based methods show particular potential in fabricating uniform semitransparent perovskite films across large areas. In this article, we review the recent progress of OHP thin-film fabrication based on vapor based deposition techniques. We discuss the instrumentation and specific features of each vapor-based method as well as its corresponding device performance. In the outlook, we outline the vapor deposition related topics that warrant further investigation.
214 citations
TL;DR: It was found that the resistance of the films decreases with increasing relative humidity (RH), and the maximum humidity sensitivity of 469% along with response time of ∼12 s and recovery time of ×13 s were observed for the WS2 thin film humidity sensor device.
Abstract: In the present investigation, we report a one-step synthesis method of wafer-scale highly crystalline tungsten disulfide (WS2) nanoparticle thin film by using a modified hot wire chemical vapor deposition (HW-CVD) technique. The average size of WS2 nanoparticle is found to be 25–40 nm over an entire 4 in. wafer of quartz substrate. The low-angle XRD data of WS2 nanoparticle shows the highly crystalline nature of sample along with orientation (002) direction. Furthermore, Raman spectroscopy shows two prominent phonon vibration modes of E12g and A1g at ∼356 and ∼420 cm–1, respectively, indicating high purity of material. The TEM analysis shows good crystalline quality of sample. The synthesized WS2 nanoparticle thin film based device shows good response to humidity and good photosensitivity along with good long-term stability of the device. It was found that the resistance of the films decreases with increasing relative humidity (RH). The maximum humidity sensitivity of 469% along with response time of ∼12 ...
211 citations
TL;DR: This work detail a reproducible method for chemical vapor deposition of monolayer, single-crystal flakes of 1T'-MoTe2 and its implementation in next-generation nanoelectronic devices.
Abstract: Growth of transition metal dichalcogenide (TMD) monolayers is of interest due to their unique electrical and optical properties. Films in the 2H and 1T phases have been widely studied but monolayers of some 1T′-TMDs are predicted to be large-gap quantum spin Hall insulators, suitable for innovative transistor structures that can be switched via a topological phase transition rather than conventional carrier depletion [Qian et al. Science 2014, 346, 1344−1347]. Here we detail a reproducible method for chemical vapor deposition of monolayer, single-crystal flakes of 1T′-MoTe2. Atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy confirm the composition and structure of MoTe2 flakes. Variable temperature magnetotransport shows weak antilocalization at low temperatures, an effect seen in topological insulators and evidence of strong spin–orbit coupling. Our approach provides a pathway to systematic investigation of monolayer, single-crystal 1T′-Mo...
208 citations
TL;DR: The as-synthesized ReSe2 flake is revealed as a novel structure, which has mirror-symmetric single-crystal domains inside, by polarization incident Raman and HRTEM.
Abstract: Hexagonal crystalline ultrathin ReSe2 flakes are synthesized for the first time by a chemical vapor deposition (CVD) method. The as-synthesized ReSe2 flake is revealed as a novel structure, which has mirror-symmetric single-crystal domains inside, by polarization incident Raman and HRTEM. The successful development of the CVD method will facilitate research on the novel anisotropic electronic/optoelectronic properties of ReSe2 in the future.
TL;DR: In this paper, a systematically study on the CVD growth of continuous bilayer ReS2 film and single crystalline hexagonal ReS 2 flake, as well as their corresponding optoelectronic properties is reported.
Abstract: Rhenium disulfide (ReS2) is attracting more and more attention for its thickness-depended direct band gap. As a new appearing 2D transition metal dichalcogenide, the studies on synthesis method via chemical vapor deposition (CVD) is still rare. Here a systematically study on the CVD growth of continuous bilayer ReS2 film and single crystalline hexagonal ReS2 flake, as well as their corresponding optoelectronic properties is reported. Moreover, the growth mechanism has been proposed, accompanied with simulation study. High-performance photodetector based on ReS2 flake shows a high responsivity of 604 A·W−1, high external quantum efficiency of 1.50 × 105 %, and fast response time of 2 ms. ReS2 film-based photodetector exhibits weaker performance than the flake one; however, it still demonstrates a much faster response time (≈103 ms) than other reported CVD-grown ReS2-based photodetector (≈104–105 ms). Such good properties of ReS2 render it a promising future in 2D optoelectronics.
TL;DR: The thermal conductivity of suspended graphene as a function of the density of defects, ND, introduced in a controllable way is investigated and an intriguing saturation-type behavior at a relatively high value of ∼400 W mK(-1) is revealed.
Abstract: We investigate the thermal conductivity of suspended graphene as a function of the density of defects, ND, introduced in a controllable way. High-quality graphene layers are synthesized using chemical vapor deposition, transferred onto a transmission electron microscopy grid, and suspended over ∼7.5 μm size square holes. Defects are induced by irradiation of graphene with the low-energy electron beam (20 keV) and quantified by the Raman D-to-G peak intensity ratio. As the defect density changes from 2.0 × 10(10) cm(-2) to 1.8 × 10(11) cm(-2) the thermal conductivity decreases from ∼(1.8 ± 0.2) × 10(3) W mK(-1) to ∼(4.0 ± 0.2) × 10(2) W mK(-1) near room temperature. At higher defect densities, the thermal conductivity reveals an intriguing saturation-type behavior at a relatively high value of ∼400 W mK(-1). The thermal conductivity dependence on the defect density is analyzed using the Boltzmann transport equation and molecular dynamics simulations. The results are important for understanding phonon - point defect scattering in two-dimensional systems and for practical applications of graphene in thermal management.
TL;DR: This investigation of the growth mechanism and temperature dependent Raman spectroscopy of chemical vapor deposited large area monolayer of MoS2, MoSe2, WS2 and WSe2 nanosheets shows that softening of Raman modes as temperature increases is due to the negative temperature coefficient and anharmonicity.
Abstract: We investigate the growth mechanism and temperature dependent Raman spectroscopy of chemical vapor deposited large area monolayer of MoS2, MoSe2, WS2 and WSe2 nanosheets up to 70 μm in lateral size. Further, our temperature dependent Raman spectroscopy investigation shows that softening of Raman modes as temperature increases from 80 K to 593 K is due to the negative temperature coefficient and anharmonicity. The temperature dependent softening modes of chemical vapor deposited monolayers of all TMDCs were explained on the basis of a double resonance phonon process which is more active in an atomically thin sample. This process can also be fundamentally pertinent in other emerging two-dimensional layered and heterostructured materials.
TL;DR: In this paper, a growth-temperature-mediated two-step chemical vapor deposition strategy is designed to synthesize MoS2 /WS2 and WS2 /MoS2 stacks on Au foils.
Abstract: A growth-temperature-mediated two-step chemical vapor deposition strategy is designed to synthesize MoS2 /WS2 and WS2 /MoS2 stacks on Au foils. Predominantly A-A stacked MoS2 /WS2 and A-B stacked WS2 /MoS2 are selectively achieved and confirmed. Relative enhancements or reductions in photocatalytic activities of MoS2 /WS2 or WS2 /MoS2 are observed under illumination, because the type-II band alignment enables directional electron flow from electrode to active site.
TL;DR: Wafer-scale and wrinkle-free epitaxial growth of multilayer hexagonal boron nitride on a sapphire substrate by using high-temperature and low-pressure chemical vapor deposition is presented.
Abstract: Large-scale growth of high-quality hexagonal boron nitride has been a challenge in two-dimensional-material-based electronics. Herein, we present wafer-scale and wrinkle-free epitaxial growth of multilayer hexagonal boron nitride on a sapphire substrate by using high-temperature and low-pressure chemical vapor deposition. Microscopic and spectroscopic investigations and theoretical calculations reveal that synthesized hexagonal boron nitride has a single rotational orientation with AA′ stacking order. A facile method for transferring hexagonal boron nitride onto other target substrates was developed, which provides the opportunity for using hexagonal boron nitride as a substrate in practical electronic circuits. A graphene field effect transistor fabricated on our hexagonal boron nitride sheets shows clear quantum oscillation and highly improved carrier mobility because the ultraflatness of the hexagonal boron nitride surface can reduce the substrate-induced degradation of the carrier mobility of two-dime...
TL;DR: In this paper, the homoepitaxial growth of phase pure (010) β-Ga2O3 thin films on a phase pure substrate by low pressure chemical vapor deposition was systematically investigated.
Abstract: This paper presents the homoepitaxial growth of phase pure (010) β-Ga2O3 thin films on (010) β-Ga2O3 substrate by low pressure chemical vapor deposition. The effects of growth temperature on the surface morphology and crystal quality of the thin films were systematically investigated. The thin films were synthesized using high purity metallic gallium (Ga) and oxygen (O2) as precursors for gallium and oxygen, respectively. The surface morphology and structural properties of the thin films were characterized by atomic force microscopy, X-ray diffraction, and high resolution transmission electron microscopy. Material characterization indicates the growth temperature played an important role in controlling both surface morphology and crystal quality of the β-Ga2O3 thin films. The smallest root-mean-square surface roughness of ∼7 nm was for thin films grown at a temperature of 950 °C, whereas the highest growth rate (∼1.3 μm/h) with a fixed oxygen flow rate was obtained for the epitaxial layers grown at 850 °C.
TL;DR: It is shown that the PL QY of CVD-grown monolayers can be improved from ∼0.1% in the as-grown case to ∼30% after treatment, with enhancement factors ranging from 100 to 1500× depending on the initial monolayer quality.
Abstract: One of the major challenges facing the rapidly growing field of two-dimensional (2D) transition metal dichalcogenides (TMDCs) is the development of growth techniques to enable large-area synthesis of high-quality materials. Chemical vapor deposition (CVD) is one of the leading techniques for the synthesis of TMDCs; however, the quality of the material produced is limited by defects formed during the growth process. A very useful nondestructive technique that can be utilized to probe defects in semiconductors is the room-temperature photoluminescence (PL) quantum yield (QY). It was recently demonstrated that a PL QY near 100% can be obtained in MoS2 and WS2 monolayers prepared by micromechanical exfoliation by treating samples with an organic superacid: bis(trifluoromethane)sulfonimide (TFSI). Here we have performed a thorough exploration of this chemical treatment on CVD-grown MoS2 samples. We find that the as-grown monolayers must be transferred to a secondary substrate, which releases strain, to obtain high QY by TFSI treatment. Furthermore, we find that the sulfur precursor temperature during synthesis of the MoS2 plays a critical role in the effectiveness of the treatment. By satisfying the aforementioned conditions we show that the PL QY of CVD-grown monolayers can be improved from ∼0.1% in the as-grown case to ∼30% after treatment, with enhancement factors ranging from 100 to 1500× depending on the initial monolayer quality. We also found that after TFSI treatment the PL emission from MoS2 films was visible by eye despite the low absorption (5-10%). The discovery of an effective passivation strategy will speed the development of scalable high-performance optoelectronic and electronic devices based on MoS2.
TL;DR: Novel Pt-Co alloyed nanocatalysts are generated via chemical vapor deposition-assisted facile one-pot synthesis with significant features is that a perfectly alloyed single-crystal structure is obtained at temperatures as low as 500 °C, which is much lower than conventional alloying temperatures.
Abstract: Novel Pt-Co alloyed nanocatalysts are generated via chemical vapor deposition-assisted facile one-pot synthesis. The method guarantees highly monodisperse Pt-Co alloy nanoparticles with precise control of metallic compositions within 1 at%. A significant features is that a perfectly alloyed single-crystal structure is obtained at temperatures as low as 500 °C, which is much lower than conventional alloying temperatures.
TL;DR: In this paper, the growth of gallium oxide thin films was carried out by Metalorganic Chemical Vapor Deposition (MOCVD) at different temperatures and the growth proceeds via coalescence of hexagonal islands and is favored when a substrate with an inplane hexagonal arrangement of the atoms is employed.
TL;DR: In this paper, the authors investigated the thermal conductivity of suspended graphene as a function of the density of defects, ND, introduced in a controllable way, and showed that the defect density changes from 2.0x10^10 cm-2 to 1.8x10−11 cm−2.
Abstract: We investigate the thermal conductivity of suspended graphene as a function of the density of defects, ND, introduced in a controllable way. Graphene layers are synthesized using chemical vapor deposition, transferred onto a transmission electron microscopy grid, and suspended over ~7.5-micrometer size square holes. Defects are induced by irradiation of graphene with the low-energy electron beam (20 keV) and quantified by the Raman D-to-G peak intensity ratio. As the defect density changes from 2.0x10^10 cm-2 to 1.8x10^11 cm-2 the thermal conductivity decreases from ~(1.8+/-0.2)x10^3 W/mK to ~(4.0+/-0.2)x10^2 W/mK near room temperature. At higher defect densities, the thermal conductivity reveals an intriguing saturation behavior at a relatively high value of ~400 W/mK. The thermal conductivity dependence on defect density is analyzed using the Boltzmann transport equation and molecular dynamics simulations. The results are important for understanding phonon - point defect scattering in two-dimensional systems and for practical applications of graphene in thermal management.
TL;DR: In this article, a three-dimensional (3D) MnO 2 -graphene oxide (GO)-CNT hybrid obtained by combining electrochemical deposition (ELD)-electrophoretic deposition (EPD) and chemical vapor deposition (CVD) is described.
TL;DR: In this article, a self-healing superhydrophobic polyvinylidene fluoride/Fe3O4@polypyrrole (F-PVDF/Fe 3O4/PolyPyrrole) fibers with core-sheath structure were successfully fabricated by electrospinning of a PVDF/fe 3O 4 mixture and in situ chemical oxidative polymerization of pyrrole, followed by chemical vapor deposition with fluoroalkyl silane.
Abstract: Self-healing superhydrophobic polyvinylidene fluoride/Fe3O4@polypyrrole (F-PVDF/Fe3O4@PPy
x
) fibers with core–sheath structure were successfully fabricated by electrospinning of a PVDF/Fe3O4 mixture and in situ chemical oxidative polymerization of pyrrole, followed by chemical vapor deposition with fluoroalkyl silane. The F-PVDF/Fe3O4@PPy0.075 fiber film produces a superhydrophobic surface with self-healing behavior, which can repetitively and automatically restore superhydrophobicity when the surface is chemically damaged. Moreover, the maximum reflection loss (R
L) of the F-PVDF/Fe3O4@PPy0.075 fiber film reaches −21.5 dB at 16.8 GHz and the R
L below −10 dB is in the frequency range of 10.6–16.5 GHz with a thickness of 2.5 mm. The microwave absorption performance is attributed to the synergetic effect between dielectric loss and magnetic loss originating from PPy, PVDF and Fe3O4. As a consequence, preparing such F-PVDF/Fe3O4@PPy
x
fibers in this manner provides a simple and effective route to develop multi-functional microwave absorbing materials for practical applications.
TL;DR: In this article, a thoroughly direct CVD approach was proposed to obtain TMDCs/h-BN vertical heterostructures without any intermediate transfer steps. The strategy enables the direct growth of single-crystal MoS2 grains of up to 200 μm2 on h-BN, which is approximately 1 order of magnitude larger than that in previous reports.
Abstract: Improved properties arise in transition metal dichalcogenide (TMDC) materials when they are stacked onto insulating hexagonal boron nitride (h-BN). Therefore, the scalable fabrication of TMDCs/h-BN heterostructures by direct chemical vapor deposition (CVD) growth is highly desirable. Unfortunately, to achieve this experimentally is challenging. Ideal substrates for h-BN growth, such as Ni, become sulfides during the synthesis process. This leads to the decomposition of the pregrown h-BN film, and thus no TMDCs/h-BN heterostructure forms. Here, we report a thoroughly direct CVD approach to obtain TMDCs/h-BN vertical heterostructures without any intermediate transfer steps. This is attributed to the use of a nickel-based alloy with excellent sulfide-resistant properties and a high catalytic activity for h-BN growth. The strategy enables the direct growth of single-crystal MoS2 grains of up to 200 μm2 on h-BN, which is approximately 1 order of magnitude larger than that in previous reports. The direct band g...
TL;DR: In this article, a large-scale SiC nanowire arrays were grown on the surface of carbon fibers via a molten-salt-assisted chemical vapor deposition process at relatively low temperature (1200°C) and the morphology, microstructure, and phase composition of the as-grown products were characterized by field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscope (HRTEM), and X-ray diffraction (XRD).
TL;DR: In this paper, high quality boron-doped diamond (BDD) electrodes with excellent electrochemical properties were deposited on niobium (Nb) substrates by hot filament chemical vapor deposition (HFCVD) method.
TL;DR: In this paper, two doping methods were compared: vapor deposition of (tridecafluoro-1,1,2,2-tetrahydrooctyl)trichlorosilane (FTS) or immersion in a solvent containing 4-ethylbenzenesulfonic acid (EBSA).
Abstract: We demonstrate how processing methods affect the thermoelectric properties of thin films of a high mobility semiconducting polymer, PBTTT. Two doping methods were compared: vapor deposition of (tridecafluoro-1,1,2,2-tetrahydrooctyl)trichlorosilane (FTS) or immersion in a solvent containing 4-ethylbenzenesulfonic acid (EBSA). Thermally annealed, thin films doped by FTS deposited from vapor yield a high Seebeck coefficient (α) at high electronic conductivity (σ) and, in turn, a large power factor (PF = α2σ) of ∼100 μW m–1 K–2. The FTS-doped films yield α values that are a factor of 2 higher than the EBSA-doped films at comparable high value of σ. A detailed analysis of X-ray scattering experiments indicates that perturbations in the local structure from either dopant are not significant enough to account for the difference in α. Therefore, we postulate that an increase in α arises from the entropic vibrational component of α or changes in scattering of carriers in disordered regions in the film.
TL;DR: In this paper, the nitrogen doped graphene was synthesized by a chemical vapor deposition method on copper foils and then they were treated with ammonia radio frequency discharge plasma to obtain a maximum doping level of 3 atomic % and a shift of valence band maximum of 0.2
TL;DR: Large‐sized MoS2 crystals can be grown on SiO2/Si substrates via a two‐stage chemical vapor deposition method using a technique used to grow transition metal dichalcogenide crystals and lateral heterojunctions.
Abstract: Large-sized MoS2 crystals can be grown on SiO2/Si substrates via a two-stage chemical vapor deposition method. The maximum size of MoS2 crystals can be up to about 305 μm. The growth method can be used to grow other transition metal dichalcogenide crystals and lateral heterojunctions. The electron mobility of the MoS2 crystals can reach ≈30 cm2 V-1 s-1, which is comparable to those of exfoliated flakes.
TL;DR: In this article, thermal vapor-deposited CsSnBr 3 perovskite solar cells are shown to show no change over the span of hours in ambient air.