The ‘ self-limiting ’ character of graphene growth on the surface of metals such as Ni and Cu makes CVD the natural choice for growing large-area and continuous graphene films. Beyond graphene, absence of the self-limiting property results in a challenge to achieving large-area, high-quality two-dimensional (2D) crystals by CVD. Recent studies of structural, optical, and electrical properties of MoS 2 -based atomic layers grown by CVD are reviewed, concluding that thermal vapor deposition will outperform thermal vapor sulfurization in producing the required materials. Whether gaseous sources will replace the now dominant solid sources in direct deposition methods is an open issue. The latest progression in various CVD techniques used in MoS 2 growth and their resultant products are discussed and compared.
Chemical Vapor DepositionVolume 21, Issue 7-8-9 p. 159-160 ContentsFree Access Chem. Vap. Deposition (7–8–9/2015) First published: 23 September 2015 https://doi.org/10.1002/cvde.201577893AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume21, Issue7-8-9September 2015Pages 159-160 RelatedInformation
Chemical Vapor DepositionVolume 21, Issue 10-11-12 MastheadFree Access Chem. Vap. Deposition (10–11–12/2015) First published: 17 December 2015 https://doi.org/10.1002/cvde.201571012AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume21, Issue10-11-12December 2015 RelatedInformation
This article presents an approach for modeling the vaporization of droplets of solvent and precursor mixture under vacuum in the pulsed-pressure (pp) CVD process. The pulsed, direct liquid injection apparatus with ultrasonic atomizer is demonstrated as a controllable and reliable alternative to the bubbler and carrier gas system. The numerical modeling solves mass, heat, and momentum continuity equations on liquid droplets, and is intended to evaluate the relative roles of the physical chemistry properties and reactor parameters in the fast vaporization of droplets. The sensitivity analysis proposed here shows that the vaporization time into the pulsed-liquid CVD system is mainly dependent on the heating available in the flash evaporation zone, then on the thermodynamic properties of the liquid solution.
High flexible SiC nanowires with diameters in the range of 10 to 50 nm and lengths of several hundred micrometers to several millimeters are synthesized using a novel catalyst‐assisted fluidized bed chemical vapor deposition method. Methyltrichlorosilane (MTS) is used as source material and particles containing cobalt were used as catalyst. The fluidized bed is specially designed to form a perpendicular uneven temperature distribution. Suspended nanosized liquid catalyst droplets are produced at middle high temperature zone and SiC nanowires are formed in situ on the catalyst droplets then accumulated at the upper part of fluidized bed. The nanowires exhibit a single crystal feature with some stacking faults. Transmission electron microscopy (TEM) analysis verifies a growth direction along the <111> axis of the nanowires. A blue shift optical emission band at about 420 nm is detected using photoluminescence spectroscopy. From the high‐resolution TEM investigation, a nanoscale smooth plane between the nanowire and the catalyst tip is observed and the two phases exhibit highly epitaxial growth interface. The growth process of the nanowires is discussed and a possible formation mechanism is proposed.
Thin films of Y2O3 are deposited on Si(100) and Al2O3 (0001) substrates via metal‐organic (MO)CVD for the first time using two closely related yttrium tris‐amidinate compounds as precursors in the presence of oxygen in the temperature range 400–700 °C. The structural, morphological, and compositional features of the films are investigated in detail. At deposition temperatures of 500 °C and higher both the precursors yield polycrystalline Y2O3 thin films in the cubic phase. The compositional analysis revealed the formation of nearly stoichiometric Y2O3. The optical band gaps are estimated using UV‐Vis spectroscopy. Preliminary electrical measurements are performed in the form of a metal oxide semiconductor (MOS) structure of Al/Y2O3/p‐Si/Ag. Leakage currents and dielectric constants are also determined.
Magnesium oxide films are deposited on glass via aerosol‐assisted (AA)CVD. Depositions using magnesium acetate tetrahydrate in ethanol or methanol are carried out at 400, 500, and 600 °C. Films are analyzed by various methods. Growth rate, film thickness, and crystallite size increase with temperature, regardless of solvent. The films are crystalline and the crystallographic preferred orientation varies with solvent and temperature, allowing fine‐tuning for industrial applications. Solvent and temperature influence the surface morphology; films deposited using ethanol consist of small surface structures compared to the featureless morphology of methanol‐derived films. The refractive index of the films is 1.72 for methanol and 1.70 for ethanol systems.
CVD is used to prepare indium tin oxide (ITO)-induced polycrystalline silicon thin films with SiH4 as the precursor. The growth of columnar polycrystalline silicon is shown. The sheet resistance (R) of ITO-induced Si thin films ranges from about 167.3 to 466.2 /sq. Light absorption increases, as does the detected transmittance, by about 18.4%-30.5% for wavelengths less than 500-700nm.
Dy2O3 doped ZrO2 films are grown on silicon substrates using atomic layer deposition at 300 °C. Dy(thd)3 (thd = 2,2,6,6‐tetramethyl‐3,5‐heptanedionato) and ZrCl4 are used as metal precursors and H2O as the oxygen precursor. Despite the low growth rate of Dy2O3 in a beta‐diketonate/water process, the process allows deposition of thin films with the dysprosium content of few mass %. The films crystallize in the form of tetragonal zirconia already in as‐deposited state and grow conformally onto 3D substrates with an aspect ratio of 1:20. The capacitors formed on the basis of the films in as‐deposited and annealed states demonstrate current–voltage and capacitance behavior characteristic of those with high‐permittivity dielectrics. The maximum concentration of electronic defects at oxide/electrode interfaces reaches 1.8 × 1011 cm−2 eV−1.
We present the direct liquid injection CVD of aluminum oxide and oxycarbide thin films using dimethylaluminum isopropoxide at high process temperature (500-700 degrees C) with the addition of O-2 gas, and at low temperature (150-300 degrees C) with the addition of H2O vapor. Very smooth films with typical roughness values lower than 2 nm are obtained. The thin films are composed of an amorphous material. The composition evolves as a function of temperature from that of a partial hydroxide to a stoichiometric oxide at low deposition temperature (150-300 degrees C), and from that of a stoichiometric oxide to a mixture of an oxide with an (oxy) carbide at higher temperature (500-700 degrees C).
A well‐designed and assembled apparatus for producing silicon nanoparticles by CO2 laser‐driven pyrolysis of SiH4 is shown. The effects of process parameters (chamber pressure, laser power, gas composition) on the nano‐silicon characteristics (average particle size, size distribution and shape) are systematically investigated. The produced silicon nanopowders are characterized and analyzed, demonstrating the produced particles are much smaller and much more uniform in size than the commercial products and those previously reported. The impressive productivity and yield are also discussed. This research allows a better understanding of the influences of processing parameters on silicon nanopowders, shows a controllable way of producing the desired powders, and paves the way to commercialization.
Remarkable developments and successes are witnessed in the fabrication and implementation of optical sensors based on localized surface plasmon resonance (LSPR) for the investigation of chemical and biological material quantities. We report on the reproducible fabrication of chemically stable surface immobilized AuNPs grown via organometallic chemical vapor deposition (OMCVD) on a polymer substrate, namely polystyrene (PS). Oxygen plasma‐treated and UV ozone‐treated PS samples depict enhanced amounts of polar ‐OH groups allowing for nucleation and growth of AuNPs. The optimum plasma treatment conditions, the largest shifts in the LSPR curves, and the bulk sensitivity of the OMCVD‐grown AuNPs are discussed.
Amorphous hydrogenated silicon oxycarbide (a-SiCO:H) thin films are produced by remote microwave hydrogen plasma CVD using 1,1,3,3-tetramethyldisiloxane precursor. The effect of substrate temperature (TS) on the chemical structure and some properties of resulting a-SiCO: H films is reported. The examination performed by infrared spectroscopy revealed that the increase in TS involves the elimination of organic moieties from the film and its transformation from polymer-like to ceramic-like high-crosslink-density material. Due to their small surface roughness, high density, and good optical transparency, the a-SiCO:H films seem to be useful coatings for optical and electronic devices.
Terbium oxide films are deposited on silicon substrates by metal‐organic (MO)CVD from a vapor of Tb(thd)3 in argon. Terbium sesquioxide (C‐form) is realized in this process. Annealing of the films in air at 800 °C, followed by cooling in air, leads to the formation of Tb4O7. The Ar ion‐etching of the annealed films causes a reduction of Tb4+ to Tb3+. Optical Eg is estimated, photoluminescence spectra are investigated, and refractive indexes and dielectric constants are measured for terbium oxide films before and after annealing in air.
The ‘ self‐limiting ’ character of graphene growth on the surface of metals such as Ni and Cu makes CVD the natural choice for growing large‐area and continuous graphene films. Beyond graphene, absence of the self‐limiting property results in a challenge to achieving large‐area, high‐quality two‐dimensional (2D) crystals by CVD. Recent studies of structural, optical, and electrical properties of MoS 2 ‐based atomic layers grown by CVD are reviewed, concluding that thermal vapor deposition will outperform thermal vapor sulfurization in producing the required materials. Whether gaseous sources will replace the now dominant solid sources in direct deposition methods is an open issue. The latest progression in various CVD techniques used in MoS 2 growth and their resultant products are discussed and compared.
Thin film bismuth vanadate (BiVO 4 ) photoelectrodes are prepared by aerosol‐assisted (AA)CVD for the first time on fluorine‐doped tin oxide (FTO) glass substrates. The BiVO 4 photoelectrodes are characterised by X‐ray diffraction (XRD), Raman spectroscopy (RS), and energy‐dispersive X‐ray (EDX) spectroscopy and are found to consist of phase‐pure monoclinic BiVO 4 . Scanning electron microscopy (SEM) analysis shows that the thin film is uniform with a porous structure, and consists of particles approximately 75−125 nm in diameter. The photoelectrochemical (PEC) properties of the BiVO 4 photoelectrodes are studied in aqueous 1 M Na 2 SO 4 and show photocurrent densities of 0.4 mA cm −2 , and a maximum incident‐photon‐to‐electron conversion efficiency (IPCE) of 19% at 1.23 V vs. the reversible hydrogen electrode (RHE). BiVO 4 photoelectrodes prepared by this method are thus highly promising for use in PEC water‐splitting cells.
Iridium thin films are deposited on sub-micrometer three-dimensional trench structures by plasma-enhanced metal-organic chemical vapor deposition (PE-MOCVD). The iridium precursor used in this study is (ethylcyclopentadienyl)(1,5-cyclooctadiene)iridium [Ir (EtCp)(1,5-COD)]. Various process conditions at substrate temperatures from 300 °C to 450 °C, with and without plasma enhancement, are investigated and compared. Crystal structure of the deposited iridium films is analyzed by X-ray diffraction (XRD). Step coverage of the deposited iridium films on three-dimensional trench structures is analyzed by scanning electron microscopy (SEM). Surface morphology is quantitatively evaluated by atomic force microscopy (AFM) and the electrical resistivity of the deposited Ir films is measured by the four-point probe method.
To deposit a film with uniform thickness, flow rectifiers are often used in a CVD reactor. Despite the effectiveness of these rectifiers, some degree of flow non-uniformity persists within the reaction chamber, due to variations in the flow and buoyancy effects. Here, the non-uniformity caused by the non-axisymmetric pumping system, specifically a single and non-annular pumping outlet, is investigated. A pumping liner, which directs the fluid mixture through embedded channels into a ring chamber connected to the pumping outlet, is used to improve flow uniformity. The flow resistance associated with each component in the pumping system is analyzed, then two carefully designed pumping liners, the channels of which either have non-uniform radii or are unevenly spaced, are proposed. The pumping effect is balanced through the non-uniform channel flow resistances, giving an axisymmetric flow field in the reaction chamber. This balance is confirmed in simulations.
Thin films of anatase titanium dioxide are deposited on fluorine-doped tin oxide (FTO) glass substrates utilizing the electric field-assisted aerosol (EA)CVD reaction of titanium isopropoxide in toluene at 450 °C. The as-deposited films are characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (RS), and UV-vis spectroscopy. The photoactivity and antibacterial activity of the films are also assessed. The characterization analysis reveals that the use of an electric field affects the film microstructure, its preferential orientation, and the functional properties. XRD of the anatase films reveals that the application of electric fields causes a change in the preferential orientation of the films from (101) to (004) or (211) planes, depending on the strength of the applied field during the deposition.
Chemical Vapor DepositionVolume 21, Issue 4-5-6 p. 94-98 Communication Synthesis of Carbon Nanotubes from Propane Mariusz Zdrojek, Corresponding Author Mariusz Zdrojek [email protected] Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, PolandSearch for more papers by this authorJan Sobieski, Jan Sobieski Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, PolandSearch for more papers by this authorAnna Duzynska, Anna Duzynska Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, PolandSearch for more papers by this authorEwa Zbydniewska, Ewa Zbydniewska Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, PolandSearch for more papers by this authorWlodek Strupinski, Wlodek Strupinski Institute of Electronic Materials Technology, Wolczynska 1335, 01-919 Warsaw, PolandSearch for more papers by this authorJacek Ratajczak, Jacek Ratajczak Institute of Electron Technology, Al. Lotnikow 32/45, 02-668 Warsaw, PolandSearch for more papers by this authorJarosław Judek, Jarosław Judek Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, PolandSearch for more papers by this author Mariusz Zdrojek, Corresponding Author Mariusz Zdrojek [email protected] Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, PolandSearch for more papers by this authorJan Sobieski, Jan Sobieski Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, PolandSearch for more papers by this authorAnna Duzynska, Anna Duzynska Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, PolandSearch for more papers by this authorEwa Zbydniewska, Ewa Zbydniewska Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, PolandSearch for more papers by this authorWlodek Strupinski, Wlodek Strupinski Institute of Electronic Materials Technology, Wolczynska 1335, 01-919 Warsaw, PolandSearch for more papers by this authorJacek Ratajczak, Jacek Ratajczak Institute of Electron Technology, Al. Lotnikow 32/45, 02-668 Warsaw, PolandSearch for more papers by this authorJarosław Judek, Jarosław Judek Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, PolandSearch for more papers by this author First published: 09 April 2015 https://doi.org/10.1002/cvde.201404329Citations: 3 This work was supported by project Lider founded by NCBR (11/22/L-2/10/NCBR/2011). AD thanks ESF for their support via WUT. We thank Leszek Stobiński for fruitful discussions. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Graphical Abstract Growth of high quality CNTs using pure propane is demonstrated over a range of growth temperatures (600–1100 °C). SWCNT and MWCNT volumes in the grown material can by tuned using the growth temperature. The SEM image shows CNTs grown at 900 °C with both SWCNTs and MWCNTs visible. Increasing temperature yields higher depositions of disordered carbon material besides NTs. References 1 A. Shaikjee, N. J. Coville, Carbon 2012, 50, 3376. 2 J. Jourdain, Ch. Bichara, Carbon 2013, 58, 2. 3 J. Sengupta, S. K. Panda, C. Jacob, Bull. Mater. Sci. 2009, 32, 135. 4 J. Sengupta, C. Jacob, J. Cryst. Growth 2009, 311, 4692. 5 N. A. Ivanova, A. A. Onischuk, S. di Stasio, A. M. Baklanov, G. A. Makhov, J. Phys. D: Appl. Phys. 2007, 40, 2071. 6 J. Kong, H. T. Soh, A. M. Cassell, C. F. Quate, H. Dai, Nature 1998, 395, 878. 7 M. Zdrojek, M. J. Esplandiu, A. Barreiro, A. Bachtold, Phys. Rev. Lett. 2009, 102, 228604. 8 B. Lassagne, D. Garcia-Sanchez, A. Aguasca, A. Bachtold, Nano Lett. 2008, 11, 3735. 9 A. Gruneis, M. J. Esplandiu, D. Garcia-Sanchez, A. Bachtold, Nano Lett. 2007, 12, 3766. 10 A. Jorio, M. Dresselhaus, R. Saito, G. F. Dresselhaus, Raman Spectroscopy in Graphene Related Systems, Wiley-VCH Veralg, 2013. 11The lower diameter tubes could be not seen in Raman spectra for 514 nm excitation line due to the lack of resonance condition. 12 A. C. Ferrari, J. Robertson, Phys. Rev. B 2000, 61, 14095. 13 M. Kumar, Y. Ando, J. Nanosci. Nanotechnol. 2010, 10, 3739. 14 A. G. Volkan, G. C. April, Ind. Eng. Chem. Process Des. Dev. 1979, 18, 232. Citing Literature Volume21, Issue4-5-6June 2015Pages 94-98 ReferencesRelatedInformation
