Multisource Deposition Research Articles

Surface acoustic wave sensor for formaldehyde gas detection using the multi-source spray-deposited graphene/PMMA composite film

A surface acoustic wave (SAW) formaldehyde sensor based on a graphene/polymethyl methacrylate (PMMA) composite film with high sensitivity, and short response and recovery time was proposed in this study. Using a novel multi-source spray deposition method, graphene sheets were uniformly dispersed in a PMMA film to fabricate sensitive films with a three-dimensional framework structure for use in SAW devices. The formaldehyde-sensing ability was enhanced by optimizing the film thickness and operating temperature. The highest performance was achieved for a graphene/PPMA film thickness of 2.2 μm at a temperature of 120°C.

Tailoring of Multisource Deposition Conditions towards Required Chemical Composition of Thin Films.

The model to tailor the required chemical composition of thin films fabricated via multisource deposition, exploiting basic physicochemical constants of source materials, is developed. The model is experimentally verified for the two-source depositions of chalcogenide thin films from Ga–Sb–Te system (tie-lines GaSb–GaTe and GaSb–Te). The thin films are deposited by radiofrequency magnetron sputtering using GaSb, GaTe, and Te targets. Prepared thin films are characterized by means of energy dispersive X-ray analysis coupled with a scanning electron microscope to determine the chemical composition and by variable angle spectroscopic ellipsometry to establish film thickness. Good agreement between results of calculations and experimentally determined compositions of the co-deposited thin films is achieved for both the above-mentioned tie-lines. Moreover, in spite of all the applied simplifications, the proposed model is robust to be generally used for studies where the influence of thin film composition on their properties is investigated.

Quadruple-Cation Wide-Bandgap Perovskite Solar Cells with Enhanced Thermal Stability Enabled by Vacuum Deposition.

Vacuum processing of multicomponent perovskites is not straightforward, because the number of precursors is in principle limited by the number of available thermal sources. Herein, we present a process which allows increasing the complexity of the formulation of vacuum-deposited lead halide perovskite films by multisource deposition and premixing both inorganic and organic components. We apply it to the preparation of wide-bandgap CsMAFA triple-cation perovskite solar cells, which are found to be efficient but not thermally stable. With the aim of stabilizing the perovskite phase, we add guanidinium (GA+) to the material formulation and obtained CsMAFAGA quadruple-cation perovskite films with enhanced thermal stability, as observed by X-ray diffraction and rationalized by microstructural analysis. The corresponding solar cells showed similar performance with improved thermal stability. This work paves the way toward the vacuum processing of complex perovskite formulations, with important implications not only for photovoltaics but also for other fields of application.

Revisiting Controls on Shale Oil Accumulation in Saline Lacustrine Basins: The Permian Lucaogou Formation Mixed Rocks, Junggar Basin

Fine-grained mixed rocks in saline lacustrine basins are important targets for shale oil exploration. However, the controls on shale oil accumulation are complex due to the multi-source mixed deposition. This is a challenging issue in the study of shale oil. Here, we present a case study in the Middle Permian Lucaogou Formation in the Jimusar Sag, Junggar Basin, northwestern China. Results show that the Lucaogou Formation consists mainly of carbonate rocks, dolomitic or calcareous mudstones, tuffaceous or silty mudstones, and siltstones. The dolomitic/calcareous mudstones (TOCaverage=6.44 wt.%) and tuffaceous/silty mudstones (TOCaverage=4.83 wt.%) have the best hydrocarbon generation potential and contain type I–II1 kerogens that are in the peak oil generation stage. However, the shale oil potential is highest for the carbonate rocks and siltstones with average oil saturation index (OSI) values of 315.03 mg HC/g TOC and 343.27 mg HC/g TOC, respectively. This indicates that hydrocarbon generation potential is not the main factor controlling shale oil potential. Micro-nanoscale pores are the main control. Abundant dissolution pores provide excellent reservoir space for near-source migration and accumulation of shale oil. Different mixing processes between lithofacies control the accumulation of shale oil, and shale oil productivity is the best when multi-facies deposition in transitional zones formed the mixed rocks (facies mixing). In addition, local accumulations of calcareous organisms and adjacent carbonate components on terrigenous sediments (in situ mixing) are also conducive to shale oil enrichment. This is an unusual and special feature of saline lacustrine shale oils, which is different from freshwater lacustrine and marine shale oils. Comprehensive assessment of source rock and reservoir is needed to robustly establish a widely applicable method to determine the shale oil potential in such basins.

Modeling and optimization of the fabrication process of thin-film solar cells by multi-source physical vapor deposition

This work presents a mathematical model describing the thin film formation during the co-evaporation of elements by PVD process for the production of CIGS type thin film photovoltaic cells. We propose a one-dimensional system of cross-diffusion Partial Differential Equations (PDEs) defined in a time-dependent space domain and introduce a numerical scheme for the discretization of the system. We calibrate our model on true experimental measurements using a dual approach. Then, in order to achieve certain targeted final concentration profiles, we consider an optimization problem that allows controlling the external atomic fluxes injected during the process. Despite its simplicity, the proposed model shows promising results towards a quantitatively predictive model. For instance, novel atomic fluxes obtained as solutions of the optimization problem could represent alternatives to the classical three-stage process. In this paper, a mathematical model describing the thin film formation during the co-evaporation PVD process for the production of CIGS type thin film photovoltaic cells is proposed.

Multisource Vacuum Deposition of Methylammonium-Free Perovskite Solar Cells.

Halide perovskites of the form ABX3 have shown outstanding properties for solar cells. The highest reported compositions consist of mixtures of A-site cations methylammonium (MA), formamidinium (FA) and cesium, and X-site iodide and bromide ions, and are produced by solution processing. However, it is unclear whether solution processing will yield sufficient spatial performance uniformity for large-scale photovoltaic modules or compatibility with deposition of multilayered tandem solar cell stacks. In addition, the volatile MA cation presents long-term stability issues. Here, we report the multisource vacuum deposition of FA0.7Cs0.3Pb(I0.9Br0.1)3 perovskite thin films with high-quality morphological, structural, and optoelectronic properties. We find that the controlled addition of excess PbI2 during the deposition is critical for achieving high performance and stability of the absorber material, and we fabricate p-i-n solar cells with stabilized power output of 18.2%. We also reveal the sensitivity of the deposition process to a range of parameters, including substrate, annealing temperature, evaporation rates, and source purity, providing a guide for further evaporation efforts. Our results demonstrate the enormous promise for MA-free perovskite solar cells employing industry-scalable multisource evaporation processes.

Oxidation Behavior Across Composition Space Relevant to Co-based γ/γ′ Alloys

A multi-source ion-plasma deposition technique was used to create a series of three combinatorial libraries across the Co-Ni-Al-W-Cr-Ta composition space relevant to the formation of Co-based γ/γ′ microstructures. Alloys were isothermally oxidized for 1 hour in air at 1100 °C, and screened for Al2O3 scale formation using a high-throughput photo-stimulated luminescence spectroscopy technique. Select compositions were then analyzed in cross-section via EDS in the SEM and TEM. The resulting oxide microstructures are presented, and paths to explain their evolution are proposed. Compositions forming α-Al2O3 with thinner amounts of overlying oxides are highlighted. The thinnest scale observed was ~ 1 μm, comparable to second-generation Ni-base superalloys oxidized under the same conditions.

4-3 多元蒸着法により作製したSrGa_2S_4 : Ce薄膜の構造及び発光特性

4-3 多元蒸着法により作製したSrGa_2S_4 : Ce薄膜の構造及び発光特性

Pt-Ni/WC Alloy Nanorods Arrays as ORR Catalyst for PEM Fuel Cells

Polymer electrolyte membrane fuel cells (PEMFCs) among the other types of fuel cells technology are attractive power sources especially for electric vehicle applications. Even though there is ongoing progress and plausible prospects of PEMFCs, there are several challenges that need to be overcome to make them successfully and economically viable. One of the most important concerns in a PEMFC is the sluggish kinetics of the cathodic oxygen reduction reaction (ORR) that requires an expensive platinum (Pt) catalyst with high weight loadings (~0.3 mg/cm2) to meet the power requirements, which is mostly responsible for the high cost of PEMFCs. Therefore, reduction in the major cost of the system can be achieved by increasing the ORR kinetics of platinum-based catalyst and by more efficient utilization of the Pt component. In addition, carbon support used in conventional Pt/C catalyst present problems including oxidation of carbon, formation of peroxide species causing degradation of polymeric membrane, and separation from the ionomer over time leading to loss of catalyst effectiveness. For this purpose, we developed vertically aligned nanorod arrays of tungsten carbide (WC) as a support and coated them with platinum-nickel (Pt-Ni) alloy shell. A glancing angle deposition (GLAD) technique was used to fabricate the WC nanorod arrays and the shell comprised of different atomic ratios of Pt:Ni prepared by a small angel deposition (SAD) technique for conformal thin film coating. We utilized a multi-source sputter deposition unit that is capable of performing GLAD and SAD in the same chamber. In our design, WC nanorods offer advantages including higher electron conductivity, thermal and chemically stability, compared to the conventional carbon support. In addition, GLAD WC nanorods are coated with SAD Pt-Ni thin film in the same deposition unit without breaking the vacuum allowing to minimize surface oxidation resulting in decreased contact resistance between Pt-Ni and WC. Moreover, Pt-Ni alloy shell can achieve superior ORR activity due to expected electronic and geometric effects. Pt-Ni/WC nanorods were deposited on glassy carbon electrodes and as well as on silicon substrates for evaluation of their electrocatalytic ORR activity and physical properties. Cyclic voltammetry and rotating disk electrode experiments were performed in a 0.1 M HClO4 electrolyte at room temperature to characterize the ORR activity and activity stability of Pt-Ni/WC nanorods. Scanning electron microscopy and X-ray diffraction methods were utilized to study morphology and crystallographic properties, respectively.

Nanolayer (Ti,Cr)N coatings for hard particle erosion resistance

This paper discusses the synthesis and characterization of titanium chromium nitride ((Ti,Cr)N) thin films deposited onto AM355 stainless steel by multi-source cathodic arc physical vapor deposition (PVD) for improved erosion resistance. The effect of Cr evaporator current and substrate bias on the erosion resistance of the (Ti,Cr)N coating were investigated. The coatings were characterized using X-ray diffraction, scanning electron microscopy, electron probe microanalysis, scanning transmission electron microscopy, scratch adhesion testing and erosion testing. The (Ti,Cr)N coatings deposited using multisource mode were determined to be nanolayered structures consisting of TiN rich and CrN rich layers. EPMA showed that the atomic percentage of Cr within the coating increased (increased Cr:Ti ratio) with increasing Cr evaporator current and that the (Ti,Cr)N chemical composition did not appear to change with varying bias. Using XRD and STEM, it was determined that all nanolayer (Ti,Cr)N coatings were multi-phased consisting of a B1 NaCl crystal structure. XRD also revealed that as the Cr evaporator current was increased, there was an increase in the CrN phase volume. Macroparticle incorporation increased with an increase in Cr evaporator current and decreased with an increase in bias. The nanolayer (Ti,Cr)N coatings ranged in Vickers hardness from 1700 to 2800 VHN0.050. Coating adhesion increased as Cr:Ti ratio increased. In regards to erosion, (Ti,Cr)N coatings with a high number of TiN/CrN interfaces performed poorly against alumina media. As the Cr evaporator current was varied, the coating deposited with the highest Cr:Ti ratio (evaporator current of 85 A) and when bias was varied, the lowest substrate bias of -50V had the best erosion performance.

ChemInform Abstract: Characteristics of SrS:CeCl3 TFEL Device Prepared by Multisource Deposition Method with H2S and Sr Metal.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Combinatorial Discovery of Platinum Alloy Electrocatalysts for Oxygen Electro-reduction

The oxygen electro-reduction properties of various platinum alloys were studied using a combinatorial high throughput method. Binary and ternary platinum alloys were fabricated using a multi-source physical vapor deposition system and the resulting thin film samples were electrochemically screened by the hydrodynamic rotating disk electrode technique. By comparing the activity-stability-composition relationship between these alloys and a pure platinum film, over 10 alloy catalyst candidates were identified with mass-fraction specific activities of 5 to 10 times that of pure platinum. Additionally, organometallic synthesis methods have been studied to synthesize carbon supported alloy nanoparticles. A good relationship of the molecular oxygen electro-reduction has been found between alloy thin film and powder catalysts.

Luminescent properties of SrGa 2S 4:Eu thin film phosphors deposited by two electron beam evaporation

SrGa 2S 4:Eu thin film phosphors have been deposited on quartz glass substrates at substrate temperatures of 350–450 °C by multi-source deposition method in which two electron beam (2EB) evaporation sources were used. The films were annealed between 750 and 850 °C for 30 min in H 2S atmosphere after the deposition. It was shown by XRD measurement that SrGa 2S 4 phase was not formed but crystalline GaS was included in an as-deposited film, therefore, PL and CL due to SrGa 2S 4:Eu were not observed. The SrGa 2S 4 phase was formed by the annealing. Photoluminescence (PL) and cathodoluminescence (CL) spectra of all annealed films showed green emission peaked at about 530 nm. CL luminance of all the films increased as the substrate temperature was increased. But the dependence on annealing temperature was not observed. So CL luminance depended only on substrate temperature during deposition. However, the CL luminance did not depend clearly on the annealing temperature between 750 and 850 °C. The SrGa 2S 4:Eu film deposited at 450 °C and annealed at 850 °C for 30 min showed a CL luminance and CIE coordinates of 1700 cd/m 2 and (0.27, 0.67), respectively under excitation with 3 kV and 60 μA/cm 2.

Luminescent properties of SrGa2S4:Sm thin-film phosphors under low-voltage excitation

Sm-activated SrGa2S4 thin-film phosphors (TFPs) were prepared in order to develop red-emitting TFPs, because so far we have reported on low-voltage cathodoluminescence (CL) properties of Ce- or Eu-activated SrGa2S4 TFPs showing blue or green emission, respectively. The films were prepared by multisource deposition (MSD), and annealed in H2S atmosphere after the deposition. It was shown by x-ray diffraction (XRD) measurement that from the as-deposited films containing GaS phase, SrGa2S4 phase was formed by the annealing. The formation mechanism of SrGa2S4 thin film is thought to be due to the reaction Sr+2GaS+2H2S→SrGa2S4+2H2↑ during the annealing. The films annealed at temperatures higher than 800 °C showed a red emission with a broad band peaked at about 700 nm, which might be based on the transition of 4f55d→4f6 of Sm2+, although the CL intensity was weak.

36.2: Multi‐Source Deposition of BaAl2S4 Blue Phosphors

AbstractMulti‐source deposition has been successfully implemented in an E‐beam system to achieve a high luminance BaAl2S4:Eu blue phosphor for TDEL application. Luminance greater than 700 cd/m2 with CIE coordinates of x = 0.135 and y = 0.105 was realized with high reproducibility. The luminous efficiency was over 1.0 lumens/W.

Influence of Preparation Conditions on the Structural and Luminescent Properties of Blue-Emitting SrGa2 S 4 : Ce Thin-Film Phosphors

Blue-emitting ternary strontium thiogallate doped with Ce thin-film phosphor has been prepared by a multisource deposition technique by employing Sr, and as the source materials. The as-deposited films show a growth of single-phase polycrystalline strontium thiogallate with poor crystallinity. Various preparation conditions such as annealing temperatures, times, and Ce concentrations have been studied with respect to structural and luminescent properties of thin films. The film annealed at elevated temperature shows an increase in crystallinity of the which leads to dissociation to SrS on the surface. The photoluminescence spectra show a typical blue emission at 445 nm independent of annealing temperatures, whereas the cathodoluminescence spectra show blue emission at 800°C and a very broad band green emission peaked at 540 nm at 900°C. The results are discussed on the basis of formation of thiogallate, stability at high temperature, luminescent properties as a function of temperature, annealing atmosphere, and Ce concentrations. © 2002 The Electrochemical Society. All rights reserved.

Cathodoluminescence properties of blue-emitting SrGa2S4:Ce thin-films grown by low-temperature process

The cathodoluminescence (CL) properties of Ce-activated strontium thiogallate (SrGa2S4:Ce) thin films have been investigated aiming towards phosphor screen application in an emissive display under low to medium accelerating voltage (<5 kV) excitation. The SrGa2S4:Ce thin films were grown by multisource deposition using a molecular beam epitaxy system. The growth temperature of the CL phosphor thin films was 472.5 °C, which is the lowest value ever achieved. Several related properties were observed, including the CL spectra, luminance, luminous efficacy, and surface morphology of the thin films. A luminance of 1000 cd/m2 and an efficacy of 1 lm/W were obtained at an accelerating voltage of 5 kV with a current density of 60 μA/cm2. The light-outcoupling efficiency (ηout) of the film was 0.0531. In spite of this small ηout of the films compared to that of powder phosphors, the luminance and efficacy were comparable to the conventional ZnS:Ag, Cl powder phosphor. The average grain size of the films was 0.14 μm×0.04 μm. The high luminance and luminous efficacy of the films with their submicron grain size is useful to realize high-resolution emissive displays.

Green electroluminescence from Zn 1– xMg xS:Mn alternating current thin film electroluminescent devices

The color shifting from yellow to green of electroluminescent emission from Zn 1– x Mg x S:Mn alternating current thin film electroluminescent (ACTFEL) devices has been achieved by changing the Mg composition in the phosphor layers. Zn 1– x Mg x S:Mn solid solution thin films in the composition range x=0–0.25 have been prepared by multi source deposition technique. The commission internationale de l'Eclairge (CIE) color co-ordinates of the ACTFEL devices prepared by these phosphor layers show a shifting from yellow ( x=0.55, y=0.45) towards green ( x=0.49, y=0.5).

Condensation and structure of multiphase thin films

Multi-source vacuum deposition processes allow manufacture of composite materials which are impossible to produce by conventional techniques. The condensation mechanisms of physical vapour deposition (PVD) may also favour the formation of new material structures which are not known from techniques such as, e.g., solidification from the melt. This paper summarizes the influence of different deposition modes on the phase distribution within vapour-deposited two-component films. Special emphasis is laid on the immiscible binary material combination Al–Sn as a model system. Two deposition modes, sequential deposition and co-deposition from two separate sources, are treated in detail. From experiments as well as from theoretical considerations, it is concluded that there are two key parameters determining the phase distribution: the different mobilities of the constituents in the growth zone and their mutual sticking coefficients. The latter parameter reflects the relation of the different surface energies. Growth models for sequential and co-deposition which reproduce the general types of phase distributions are formulated. Methods of a detailed morphological characterization of the single phases are presented. Finally possible influences of impurities present at the growth front of two component films on the mobilities and surface energies of the constituents are discussed.

Chemical changes of polymeric surfaces after modification with multi-source cluster deposition

A new process for surface modification of polymers with multi-source cluster deposition apparatus has been reported in our previous work. The apparatus simultaneously supplies reactant of ammonium sulfamate and activator of energetic Ar + ion. In this work chemical changes are analyzed on the basis of XPS spectra and the relations of contact angle and platelet adhesion with chemical changes are discussed. Polymer film, setting on a turning holder, was irradiated by Ar + ions during bombardment with ammonium sulfamate clusters. The Ar + ion source served for activation of polymer surface and a cluster ion source supplied ammonium sulfamate molecules to react with activated surface. After thorough washing with deionized sterile water, the modified surfaces were evaluated in terms of contact angle of water, elemental composition and binding state on XPS and platelet adhesion with platelet rich plasma (PRP). The modification of polysulfone decreased the contact angle of water on surfaces from 82.6 down to 34.5°. The adhesion number of platelets were decreased to one-tenth of the original surface. Ammonium, amine, sulfate and thiophene combinations were formed on the modified surfaces. The primary studies showed successful modification of polysulfone with ammonium sulfamate by assistance of Ar + ion irradiation. The polar groups like N-sulfate were formed on surfaces and contribute to the decrease of surface contact angle and adhesion number of platelets. Since the same process can also be applied to other polymeric materials with various substrates, combining with the features of no solvent and no topographic changes, this method might be developed in a promising way for modification of polymers.