Showing papers on "Evaporation (deposition) published in 2015"
IBM1
451 citations
TL;DR: Reactive multilayer thin films are a class of energetic materials that continue to attract attention for use in joining applications and as igniters as discussed by the authors, with most of these materials fabricated by magnetron sputter deposition or electron-beam evaporation.
216 citations
TL;DR: The growth of epitaxial MoS2-graphene heterostructures on SiC opens new opportunities for further in situ studies of the fundamental properties of these complex materials, as well as perspectives for implementing them in various device schemes to exploit their many promising electronic and optical properties.
Abstract: In this work, we demonstrate direct van der Waals epitaxy of MoS2–graphene heterostructures on a semiconducting silicon carbide (SiC) substrate under ultrahigh vacuum conditions. Angle-resolved photoemission spectroscopy (ARPES) measurements show that the electronic structure of free-standing single-layer (SL) MoS2 is retained in these heterostructures due to the weak van der Waals interaction between adjacent materials. The MoS2 synthesis is based on a reactive physical vapor deposition technique involving Mo evaporation and sulfurization in a H2S atmosphere on a template consisting of epitaxially grown graphene on SiC. Using scanning tunneling microscopy, we study the seeding of Mo on this substrate and the evolution from nanoscale MoS2 islands to SL and bilayer (BL) MoS2 sheets during H2S exposure. Our ARPES measurements of SL and BL MoS2 on graphene reveal the coexistence of the Dirac states of graphene and the expected valence band of MoS2 with the band maximum shifted to the corner of the Brillouin ...
148 citations
TL;DR: An exceptionally good control over theMoS2 coverage is maintained using an approach based on cycles of Mo evaporation and sulfurization to first nucleate the MoS2 nanoislands and then gradually increase their size.
Abstract: We present a method for synthesizing large area epitaxial single-layer MoS2 on the Au(111) surface in ultrahigh vacuum. Using scanning tunneling microscopy and low energy electron diffraction, the evolution of the growth is followed from nanoscale single-layer MoS2 islands to a continuous MoS2 layer. An exceptionally good control over the MoS2 coverage is maintained using an approach based on cycles of Mo evaporation and sulfurization to first nucleate the MoS2 nanoislands and then gradually increase their size. During this growth process the native herringbone reconstruction of Au(111) is lifted as shown by low energy electron diffraction measurements. Within the MoS2 islands, we identify domains rotated by 60° that lead to atomically sharp line defects at domain boundaries. As the MoS2 coverage approaches the limit of a complete single layer, the formation of bilayer MoS2 islands is initiated. Angle-resolved photoemission spectroscopy measurements of both single and bilayer MoS2 samples show a dramatic ...
124 citations
TL;DR: In this article, the authors provide details on the development of instrumentation and methodology to overcome the common difficulties that the vacuum-related techniques face for fabrication of perovskite thin films.
Abstract: We provide details on the development of instrumentation and methodology to overcome the common difficulties that the vacuum-related techniques face for fabrication of perovskite thin films and perovskite solar cells (PSCs). Our methodology relies on precisely controlling the flow of methylammonium iodide (CH3NH3I, MAI), which has a high-vapor pressure nature, and the deposition rate of metal halides (PbCl2 or PbI2). This hybrid deposition method allows the growth of perovskite films with smooth surface, good crystallinity, high surface coverage, uniform chemical composition and semi-transparency. We also systematically investigated the effects of the evaporation source materials (PbCl2 : MAI versus PbI2 : MAI), substrate temperatures, and post-annealing on the properties of perovskite films, as well as device performances based on this method. By employing a thin perovskite film (<200 nm), the power conversion efficiency of PSC can be as high as 11.5%.
122 citations
TL;DR: In this article, a significant efficiency improvement to 4.8% of superstrate cadmium sulfide (CdS)/Sb2Se3 solar cells is obtained by the controlled addition of oxygen during thermal evaporation of Sb 2Se3 films.
Abstract: Sb2Se3 has attracted great research interest very recently as a promising absorber material for thin film photovoltaics due to its suitable bandgap, high absorption coefficient, and non-toxic, low cost, and earth abundant nature. In this work, a significant efficiency improvement to 4.8% of superstrate cadmium sulfide (CdS)/Sb2Se3 solar cells is obtained by the controlled addition of oxygen during thermal evaporation of Sb2Se3 films. Systematic materials and device physics characterization reveal that oxygen addition during Sb2Se3 film evaporation significantly improves the CdS/Sb2Se3 heterojunction quality through effective passivation of interfacial defect states, resulting in a substantial enhancement in device circuit voltage and short circuit current density. The 4.8% device is the highest efficiency thus far reported for Sb2Se3 thin film solar cells. Copyright © 2015 John Wiley & Sons, Ltd.
114 citations
TL;DR: In this article, the electron transport layer (ETLTL) of planar junction perovskite solar cells was used as a transport layer for electron beam (e-beam) induced evaporation, which achieved power conversion efficiency of 14.6% on glass and 13.5% on flexible plastic substrates.
Abstract: The TiO2 layer made by electron beam (e-beam) induced evaporation is demonstrated as an electron transport layer (ETL) in high efficiency planar junction perovskite solar cells. The temperature of the substrate and the thickness of the TiO2 layer can be easily controlled with this e-beam induced evaporation method, which enables the usage of different types of substrates. Here, perovskite solar cells based on CH3NH3PbI3−xClx achieve power conversion efficiencies of 14.6% on glass and 13.5% on flexible plastic substrates. The relationship between the TiO2 layer thickness and the perovskite morphology is studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Our results indicate that the pinholes in the thin TiO2 layer lead to pinholes in the perovskite layer. By optimizing the TiO2 thickness, perovskite layers with substantially increased surface coverage and reduced pinhole areas are fabricated, increasing overall device performance.
112 citations
TL;DR: In this paper, the effect of multilayer coating on the corrosion resistance of zirconium alloys at test temperatures between 660 and 1100°C for 3600 s has been investigated.
110 citations
TL;DR: In this article, the authors showed that the optimal growth temperature of SnS by the evaporation is 200°C, giving rise to compact and large crystal grains and the highest Hall mobility, thereby contributing to the 2.53%-efficient SnS thin-film solar cell.
90 citations
TL;DR: A Si/porous reduced graphene oxide (rGO) composite film synthesized by evaporation and leavening method is developed as a high-performance anode material for lithium ion batteries.
84 citations
TL;DR: In this article, the influence of Ti doping on structural, morphological, optical and UV detection properties of zinc oxide (ZnO) thin films was studied, which revealed that the ZnO film was polycrystalline with a hexagonal wurtzite structure.
TL;DR: By changing the conditions such as drop size and concentration, supraparticles of different sizes, compositions, and architectures are fabricated by the evaporation of nanoparticle dispersion drops on the superamphiphobic surface.
Abstract: A method for mesoporous supraparticle synthesis on superamphiphobic surfaces is designed. Therefore, supraparticles assembled with nanoparticles are synthesized by the evaporation of nanoparticle dispersion drops on the superamphiphobic surface. For synthesis, no further purification is required and no organic solvents are wasted. Moreover, by changing the conditions such as drop size and concentration, supraparticles of different sizes, compositions, and architectures are fabricated.
01 Jan 2015
TL;DR: In this paper, the authors discuss the application and development of thin film technology, and the importance of the vacuum technology for thin film coatings, as well as the applications and developments of thin-film technology.
Abstract: Applications and developments of thin film technology.- Importance of the vacuum technology for thin film coatings.- Evaporation in the vacuum.- Basic principle of plasma physics.- Gaseous phase and surface processes.- Coating by cathode sputtering.- Plasma treatment methods.- Ion beam-supported procedures.- Chemical Vapor Deposition (CVD).- Physical basics of modern methods of surface and thin film analysis.- Measurements of thin layers during the coating.- Measurements of thin layers after terminated coating process.- Nanoparticle Films.- Optical properties of thin films.
TL;DR: The effect of substrate temperature on the growth of CTS thin films has been investigated in this paper, where the authors reported the deposition of Cu 2 SnS 3 thin films on soda-lime glass substrate by co-evaporation technique at different substrate temperatures.
TL;DR: A mixture of purely light absorptive plasmonic nanostructures such as gold nanoparticles and purely scattering particles (polystyrene nanoparticles) are employed to confine the incident light at the top of the solution and convert light to heat.
Abstract: This report investigates the enhancement of localized evaporation via separated light absorbing particles (plasmonic absorbers) and scattering particles (polystyrene nanoparticles). Evaporation has been considered as one of the most important phase-change processes in modern industries. To improve the efficiency of evaporation, one of the most feasible methods is to localize heat at the top water layer rather than heating the bulk water. In this work, the mixture of purely light absorptive plasmonic nanostructures such as gold nanoparticles and purely scattering particles (polystyrene nanoparticles) are employed to confine the incident light at the top of the solution and convert light to heat. Different concentrations of both the light absorbing centers and the light scattering centers were evaluated and the evaporation performance can be largely enhanced with the balance between absorbing centers and scattering centers. The findings in this study not only provide a new way to improve evaporation efficiency in plasmonic particle-based solution, but also shed lights on the design of new solar-driven localized evaporation systems.
TL;DR: The precise stoichiometric control of methylammonium lead iodide perovskite thin-films using high vacuum dual-source vapor-phase deposition is presented and the I-V hysteresis was unaffected by varying the film stoichiometry.
Abstract: Herein, we present the precise stoichiometric control of methlyammonium lead iodide perovskite thin-films using high vacuum dual-source vapor-phase deposition. We found that UV/Vis absorption and emission spectra were inadequate for assessing precisely the perovskite composition. Alternatively, inductively coupled plasma mass spectrometry (ICP-MS) is used to give precise, reproducible, quantitative measurements of the I/Pb ratio without systematic errors that often result from varying device thicknesses and morphologies. This controlled deposition method enables better understanding of the evaporation and deposition processes; methylammonium iodide evaporation appears omnidirectional, controlled using the chamber pressure and incorporated in the film through interaction with the unidirectionally evaporated PbI2. Furthermore, these thin-films were incorporated into solar cell device architectures with the best photovoltaic performance and reproducibility obtained for devices made with stoichiometric perovskite active layers. Additionally, and particularly pertinent to the field of perovskite photovoltaics, we found that the I-V hysteresis was unaffected by varying the film stoichiometry.
TL;DR: It is found that gold nanoparticles, when heated to close to their melting point on substrates of amorphous SiO2 or amorphously Si3N4, move perpendicularly into the substrate.
Abstract: We found that gold nanoparticles, when heated to close to their melting point on substrates of amorphous SiO2 or amorphous Si3N4, move perpendicularly into the substrate. Dependent on applied temperatures, particles can become buried or leave nanopores of extreme aspect ratio (diameter congruent to 25 nm, length up to 800 nm). The process can be understood as driven by gold evaporation and controlled by capillary forces and can be controlled by temperature programming and substrate choice.
TL;DR: In this paper, a superhydrophobic CuO/Mg/fluorocarbon nanoenergetic composite is prepared on the silicon substrate by E-beam evaporation and sputtering.
TL;DR: The obtained surfaces exhibited a low cytotoxicity toward human mesenchymal stem cells, being therefore promising candidates for fabricating implantable biomaterials with increased biocompatibility and resistance to microbial colonization and further biofilm development.
Abstract: We report on thin film deposition by matrix-assisted pulsed laser evaporation of simple hydroxyapatite (HA) or silver (Ag) doped HA combined with the natural biopolymer organosolv lignin (Lig) (Ag:HA-Lig). Solid cryogenic target of aqueous dispersions of Ag:HA-Lig composite and its counterpart without silver (HA-Lig) were prepared for evaporation using a KrF* excimer laser source. The expulsed material was assembled onto TiO2/Ti substrata or silicon wafers and subjected to physical-chemical investigations. Smooth, uniform films adherent to substratum were observed. The chemical analyses confirmed the presence of the HA components, but also evidenced traces of Ag and Lig. Deposited HA was Ca deficient, which is indicative of a film with increased solubility. Recorded X-ray Diffraction patterns were characteristic for amorphous films. Lig presence in thin films was undoubtedly proved by both X-ray Photoelectron and Fourier Transform Infra-Red Spectroscopy analyses. The microbiological evaluation showed that the newly assembled surfaces exhibited an inhibitory activity both on the initial steps of biofilm forming, and on mature bacterial and fungal biofilm development. The intensity of the anti-biofilm activity was positively influenced by the presence of the Lig and/or Ag, in the case of Staphylococcus aureus, Pseudomonas aeruginosa and Candida famata biofilms. The obtained surfaces exhibited a low cytotoxicity toward human mesenchymal stem cells, being therefore promising candidates for fabricating implantable biomaterials with increased biocompatibility and resistance to microbial colonization and further biofilm development.
TL;DR: In this article, a facile and environmentally friendly hexane-assisted one-step solution approach for dense and uniform CH3NH3PbI3 thin films was proposed, where n-hexane was chosen as the assistant solvent to speed up the evaporation of the main solvent N,N-dimethylformamide (DMF) during the solution deposition process.
Abstract: The morphology and crystal structure of perovskite films are critical for achieving high-performance perovskite solar cells; however in most cases, the conventional one-step solution deposition method hardly yields a homogeneous perovskite film over a large area, especially for CH3NH3PbI3. Here, we propose a facile and environmentally friendly hexane-assisted one-step solution approach for dense and uniform CH3NH3PbI3 thin films. According to the phase diagram of immiscible liquids, n-hexane was chosen as the assistant solvent to speed-up the evaporation of the main solvent N,N-dimethylformamide (DMF) during the solution deposition process, thus significantly promoting the nucleation and crystallization process of CH3NH3PbI3 perovskite. The as-prepared CH3NH3PbI3 films demonstrated a uniform and dense morphology, and enhanced light absorption in a long-wavelength range. In particular, such n-hexane treatment could help eliminate the residual DMF and greatly improve the thermal stability of the obtained perovskite films. The full solution-processed CH3NH3PbI3 solar cells using n-hexane treatment exhibited a maximum power conversion efficiency of 11.7% and average efficiencies of 11.3 ± 0.4% under standard AM 1.5 conditions in comparison with 7.0 ± 0.4% of the conventional cells. The recombination resistance of the cells increased nearly 5 times by using n-hexane. These results suggest that this hexane-assisted one-step solution approach is promising for controlling the crystallization process of perovskites to achieve high-performance perovskite solar cells.
TL;DR: In this article, a silica mesoporous thin film, synthesized through the evaporation induced self-assembly process, was doped with benzotriazole to obtain active corrosion protection.
TL;DR: In this article, the results of the deposition of chromium nitride coatings on HS6-5-2 steel substrates on the front and reverse side of the substrates with respect to the cathode by cathodic arc evaporation were analyzed.
TL;DR: A maximum fluorescent quantum yield of 16% was realized under the optimum conditions, and this value is extremely high compared to values previously reported on gold NPs and clusters (generally ∼1%).
Abstract: This paper proposes a novel methodology to synthesize highly fluorescent gold nanoparticles (NPs) with a maximum quantum yield of 16%, in the near-infrared (IR) region. This work discusses the results of using our (previously developed) matrix sputtering method to introduce mercaptan molecules, α-thioglycerol, inside the vacuum sputtering chamber, during the synthesis of metal NPs. The evaporation of α-thioglycerol inside the chamber enables to coordinate to the “nucleation stage” very small gold nanoclusters in the gas phase, thus retaining their photophysical characteristics. As observed through transmission electron microscopy, the size of the Au NPs obtained with the addition of α-thioglycerol varied from approximately 2–3 nm to approximately 5 nm. Plasmon absorption varied with the size of the resultant nanoparticles. Thus, plasmon absorption was observed at 2.4 eV in the larger NPs. However, it was not observed, and instead a new peak was found at approximately 3.4 eV, in the smaller NPs that result...
TL;DR: This study reports the application of fast water permeation property of immersed GO deposition for enhancing the performance of a GO/water nanofluid charged two-phase closed thermosyphon (TPCT).
Abstract: The unique characteristic of fast water permeation in laminated graphene oxide (GO) sheets has facilitated the development of ultrathin and ultrafast nanofiltration membranes. Here we report the application of fast water permeation property of immersed GO deposition for enhancing the performance of a GO/water nanofluid charged two-phase closed thermosyphon (TPCT). By benchmarking its performance against a silver oxide/water nanofluid charged TPCT, the enhancement of evaporation strength is found to be essentially attributed to the fast water permeation property of GO deposition instead of the enhanced surface wettability of the deposited layer. The expansion of interlayer distance between the graphitic planes of GO deposited layer enables intercalation of bilayer water for fast water permeation. The capillary force attributed to the frictionless interaction between the atomically smooth, hydrophobic carbon structures and the well-ordered hydrogen bonds of water molecules is sufficiently strong to overcome the gravitational force. As a result, a thin water film is formed on the GO deposited layers, inducing filmwise evaporation which is more effective than its interfacial counterpart, appreciably enhanced the overall performance of TPCT. This study paves the way for a promising start of employing the fast water permeation property of GO in thermal applications.
TL;DR: In this article, the effects of transition metal additives on the oxidation behavior of ZrB2 ceramics at 1600°C were investigated, and it was shown that Mo or Nb were more effective than W at improving the oxidation resistance.
TL;DR: The optical and electrical improvement all suggest that thermal evaporation is the appropriate method to further enhance device performance.
Abstract: Generally, the surface plasmon resonance (SPR) effect of metal nanoparticles is widely applied on polymer solar cells (PSCs) to improve device performance by doping method into solution. Herein, a diameter-controlled thermally evaporation method was used to realize Au nanoparticles (Au NPs) doping into WO3 anode buffer layer in inverted PSCs. The surface energy differences between Au and WO3 inevitably lead to Au growing up through the process from nucleation, isolated island, aggregation of metal islands to continuous films along with the process of evaporation. The atom force microscopy (AFM) images indicate that critical thickness of Au film formation is 8 nm, which is in accordance with current density–voltage (J–V) and incident photon-to-electron conversion efficiency (IPCE) measurement results of optimal device performance. The power conversion efficiency (PCE) with 8 nm Au is dramatically improved from 4.67 ± 0.13% to 6.63 ± 0.17% compared to the one without Au. Moreover, the optical absorption enh...
TL;DR: In this paper, a simple vacuum evaporation technique was used to realize BaSi2 films for solar cell applications, and X-ray diffraction analysis showed that single-phase BaSi-2 films are formed on alkali-free glass substrates at 500 and 600 °C while impurity phases coexist on quartz or soda-lime glass substrate or at a substrate temperature of 400 °C.
Abstract: We have realized BaSi2 films by a simple vacuum evaporation technique for solar cell applications. X-ray diffraction analysis shows that single-phase BaSi2 films are formed on alkali-free glass substrates at 500 and 600 °C while impurity phases coexist on quartz or soda-lime glass substrates or at a substrate temperature of 400 °C. The mechanism of film growth is discussed by analyzing the residue on the evaporation boat. An issue on the fabricated films is cracking due to thermal mismatch, as observed by secondary electron microscopy. Optical characterizations by transmittance and reflectance spectroscopy show that the evaporated films have high absorption coefficients, reaching 2 × 104 cm−1 for a photon energy of 1.5 eV, and have indirect absorption edges of 1.14–1.21 eV, which are suitable for solar cells. The microwave-detected photoconductivity decay measurement reveals that the carrier lifetime is approximately 0.027 µs, corresponding to the diffusion length of 0.84 µm, which suggests the potential effective usage of photoexcited carriers.
TL;DR: In this paper, the formation of multilayer graphene (MLG) was confirmed by Raman spectroscopy and a heterojunction was fabricated by sol-gel coating of TiO2 on CVD grown graphene layer.
Abstract: Thermally oxidized p-type Si [resistivity (5–10) Ω cm and 〈1 0 0〉 orientation] with oxide thickness of 245 nm was used as the substrate for the deposition of graphene by CVD. The formation of multilayer graphene (MLG) was confirmed by Raman spectroscopy. A heterojunction was fabricated by sol–gel coating of TiO2 on CVD grown graphene layer. The formation of titanium dioxide was verified by electron dispersion spectroscopy (EDS). The surfaces of TiO2, graphene as well as p-TiO2/n-graphene interface were characterized by scanning electron microscopy (SEM). Detail sensor study of the p-TiO2/n-graphene heterojunction was performed by taking two lateral catalytic metal (Pd) contacts deposited by e-beam evaporation. The response time of 16 s and the corresponding recovery time of 61 s were obtained for 0.5% H2 in air at 125 °C. The p-TiO2/n-graphene junction showed selectivity for H2 compared to methane. The stability study was performed and it showed almost the steady results over a period of 3 days as tested by the discrete measurements. The sensing mechanism was formulated using a simplified energy band diagram.
TL;DR: In this paper, the composition of the thin film was approximately constant regardless changing Sn mole ratio in the precursor, however, the composition inside of thin films and Mo layer had gradation.
Abstract: Cu2SnS3 thin films were prepared by crystallization in sulfur and tin mixing atmosphere from the stacked Cu/Sn precursors deposited by sequential evaporation of Sn and Cu elements. From EPMA analysis, the composition of the thin film was approximately constant regardless changing Sn mole ratio in the precursor. However, the composition of inside of the thin films and Mo layer had gradation. The Raman analysis showed that the spectrum corresponded to monoclinic Cu2SnS3. Cu2SnS3 thin films were applied to the fabrication of Cu2SnS3 solar cells. The values of Voc and Isc increased with decreasing Sn mole ratio in the precursor. The largest Voc of 247.5 mV was achieved in sample of Cu/Sn mole ratio of 2/1.2, which is comparable with early reported value of Voc. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, the effects of change in radio frequency (RF) power and deposition pressure on the structural and optical properties of the films have been investigated, and the lattice parameter, film thickness and optical band gap are found to be strongly dependent on the deposition pressure.
Abstract: Highly crystalline copper nitride (Cu 3 N) thin films have been deposited on glass substrates at room temperature by a novel and commercially viable growth technique, known as modified activated reactive evaporation (MARE). The effects of change in radio frequency (RF) power and deposition pressure on the structural and optical properties of the films have been investigated. RF power plays a significant role for the preferential growth of these films along a particular plane whereas the deposition pressure has comparatively lesser impact on the same. However, the lattice parameter, film thickness and optical band gap are found to be strongly dependent on the deposition pressure. The MARE grown Cu 3 N films undergo complete decomposition into metallic Cu upon vacuum annealing at 400 °C which makes them promising candidates to be used in write once optical recording media.