Influence Of Deposition Parameters Research Articles

Plasma Enhanced Atomic Layer Deposition of Tantalum (V) Oxide

The tantalum oxide thin films are promising materials for various applications: as coatings in optical devices, as dielectric layers for micro and nanoelectronics, and for thin-films solid-state lithium-ion batteries (SSLIBs). This article is dedicated to the Ta-O thin-film system synthesis by the atomic layer deposition (ALD) which allows to deposit high quality films and coatings with excellent uniformity and conformality. Tantalum (V) ethoxide (Ta(OEt)5) and remote oxygen plasma were used as tantalum-containing reagent and oxidizing co-reagent, respectively. The influence of deposition parameters (reactor and evaporator temperature, pulse and purge times) on the growth rate were studied. The thickness of the films were measured by spectroscopic ellipsometry, scanning electron microscopy and X-ray reflectometry. The temperature range of the ALD window was 250–300 °C, the growth per cycle was about 0.05 nm/cycle. Different morphology of films deposited on silicon and stainless steel was found. According to the X-ray diffraction data, the as-prepared films were amorphous. But the heat treatment study shows crystallization at 800 °C with the formation of the polycrystalline Ta2O5 phase with a rhombic structural type (Pmm2). The results of the X-ray reflectometry show the Ta-O films’ density is 7.98 g/cm3, which is close to the density of crystalline Ta2O5 of the rhombic structure (8.18 g/cm3). The obtained thin films have a low roughness and high uniformity. The chemical composition of the surface and bulk of Ta-O coatings was studied by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. Surface of the films contain Ta2O5 and some carbon contamination, but the bulk of the films does not contain carbon and any precursor residues. Cyclic voltammetry (CVA) showed that there is no current increase for tantalum (V) oxide in a potential window of 3–4.2 V and has prospects of use as protective coatings for cathode materials of SSLIBs.

Galvanic deposited Ni-Ir electrocatalyst for electrolysers

In this study, iridium- nickel- catalysts were galvanostatically prepared from different iridium salts. The influence of deposition parameters and bath composition on surface morphology, alloy composition and catalytic properties for the hydrogen evolution reaction was determined. Oxalic acid was determined as complexing agent and improved the iridium incorporation rate and efficiency. The achieved alloy compositions ranged from 6% to 70% iridium, with best results for the hydrogen evolution reaction (HER) coming from an electrode with 70% iridium.

Computational thermodynamic study of SiC chemical vapor deposition from MTS‐H2*

AbstractThis study focuses on the computational thermodynamic analysis of the chemical vapor deposition (CVD) of SiC from the methyltrichlorosilane‐hydrogen (MTS‐H2) using up‐to‐date thermodynamic databases. High‐resolution computation has been performed with the fine intervals of temperature and pressure at the various H2/MTS ratios of interest to systematically investigate the deposition condition range (800 to 1600°C, 0 to 26 664 Pa, and H2/MTS ratios of 0.1 to 100) to guide experimental exploration. The influence of deposition parameters on the compositions and phase stabilities of the deposit and gas phase pertinent to vapor processing is elucidated. Low pressure and medium temperatures (1000 to 1400°C) are beneficial to reaching a higher SiC deposition efficiency and provide an optimal window for preparing a high‐purity (>99 wt.% SiC) deposit. This optimal processing window expands significantly with an increasing H2/MTS ratio (<20). These results are supported by a number of previous theoretical and experimental observations. The mass fraction of SiC in deposit is proposed as an additional perspective to understand the discrepancy between thermodynamic calculation and experimental observation of pure CVD SiC at low H2/MTS ratios.

Development of Multi-Layer Fabrication Process for SFQ Large Scale Integrated Digital Circuits

We have developed a fabrication technology for the development of large-scale superconducting integrated circuits with Nb-based Josephson junctions. The standard fabrication process with 10 mask levels uses four metal layers including 3 Nb superconducting layers and a Mo resistor layer. The influence of deposition parameters on film stress, electrical properties, and surface roughness were studied systematically. High quality Nb, Al, Mo, and SiO2 films were successfully deposited for the subsequent fabrication of circuits. The circuit fabrication started with the fabrication of Mo resistors with a target sheet resistance Rsh of 2 Ome, followed by the deposition of Josephson-junction. The target critical current density Jc was set at 6 kA per cm2. The thicknesses and etch depths of the films were monitored during fabrication with on-wafer process-control-monitor (PCM) patterns for all the wafers.

Influence of deposition parameters on surface morphology and application of CuInS2 thin films in solar cell and photocatalysis

Copper indium disulfide (CuInS2) thin films as an absorption layer for solar cell and photocatalytic degradation of organic pollutants, were successfully electrodeposited on the FTO coated glass substrate using the simple and inexpensive electrodeposition method and a sulfurization process. The effects of the Cu/In molar ratio, annealing temperature and kind of Cu2+ precursor (Cu(salen) and Cu(acac)2 as novel Cu2+ precursors) on the structural and morphological properties of samples were examined. The XRD diffraction patterns and energy dispersive spectroscopy measurements exhibit that high-quality film with superior crystalline structure was formed in the presence of Cu(salen) as Cu2+ precursor. Also, we found that a suitable heat treatment temperature could suppress the CuS phases and form well-crystallized CIS. As we know, this is the first reported efficiency for any CuInS2 superstrate solar cell to date that fabricated using Cu(salen) as Cu2+ precursor. In addition, the photocatalytic degradation of organic dye in the presence of as-synthesized CuInS2 thin films was studied. The as-prepared semiconductor photocatalysts have a good reusability; it can be successfully reused for 5 times recycling photoactivity tests.

Synthesis of TiN, Ti, and TiSi2 Thin Films for the Contact System of Solar Cells

The influence of deposition parameters, such as: the magnetron power in the range 690–1400 W, the silicon substrate temperature 23–170°C, the N2 gas flow rate 0.9–3.6 L/h, the Ar gas flow rate 0.06‒3.6 L/h, the ratio of N2/Ar gas flows 1–60 on the thickness, the density, and the composition of the deposited films is analyzed. The maximum density 5.247 g/cm3 corresponding to the TiN0.786 = Ti56N44 composition has been achieved at the following deposition parameters: 1200 W, N/Ar = 1.8/0.06 L/h = 30, 0.8 Pa, 320 s, and 100°C. At temperatures 700–800°C, the mutual diffusion of titanium and silicon atoms through the interface leads to the active nucleation, the formation of nanocrystals and low-resistance metallization layers. X-ray diffraction shows that, during annealing at 700°C (30 min, Ar), the formation of phase TiSi2 due to the diffusion of Ti atoms into silicon is twice more intense than the formation of Ti5Si3 due to the diffusion of silicon atoms into titanium as a result of high hardness of titanium. The average sizes of TiSi2 decreases from 7.1 to 5.6 nm at 750°C due to the crystallization of the nuclei and increase to 9.2 nm at 800°C.

Characterization of Zinc Sulphide thin films prepared using RF-sputtering technique

Nanocrystalline Zinc Sulphide (ZnS) thin films were synthesized via RF magnetron sputtering technique on glass substrates. The influence of deposition parameters and post- deposition thermal annealing on the structural, morphological and optical properties was studied in detail. X-ray diffraction studies revealed the nanocrystalline nature of the films along with their crystalline perfection, indicated by the preferential orientation of the grains. Thin films were prepared with RF power ranging 100 W–250 W. The depositions were also performed for three different sputtering durations (10, 20, 30 min) with fixed RF power and also studied the effects of thermal annealing on the structural and optical properties of ZnS thin films. The films were characterized by x-ray diffraction (XRD), Scanning Electron Microscope and UV–Visible Spectroscopy.

Synthesis of gold nanostructures using wet chemical deposition in SiO2/Si template

The size and interposition of particles is a key parameter for the practical application of metallic nanostructures which requires the development of a synthesis method with precise control over their parameters. In this work the method for the synthesis of gold nanostructures in the pores of silicon dioxide from a gold sulfite complex and a gold chloride solution via wet chemistry technique was proposed. The influence of deposition parameters, such as deposition temperature and electrolyte composition, on the deposit morphology was studied. It was shown that gold agglomerates were unevenly distributed over the silicon surface at high temperatures and practically uniformly distributed with temperature decrease. Addition of fluoric acid at the deposition stage defines the metal precipitation selectivity into the silicon oxide pores. The peculiarities of gold nanostructures formation mechanism were discussed.

Growth rate and surface free energy of diamond films using different gas-sources

ABSTRACTFor diamond multilayer structure film (low residual stress and good toughness), the monolayer thickness and surface properties have an important effect on the quality of multilayer film. Therefore, the influence of deposition parameters on the quality, growth rate and surface free energy of diamond films was investigated in CH4/H2, CH4/H2/Ar and CH4/H2/N2 respectively. The results show that the nano-crystalline diamond films can be prepared in three different gas sources. The growth rate significantly increases with increasing CH4 and N2 content, but it increased at first and then decreased with increasing the Ar content. Surface roughness shows a downward trend with increasing of CH4 and Ar, as well as the addition of N2. The surface free energy decreases with the decrease of the surface roughness and film purity. Finally, the average growth rate and surface free energy of the nano-crystalline diamond film can be controlled by adjusting the deposition parameters.

The semi-conductor of ZnO deposited in reactive HiPIMS

In this paper we report the semi-conductor of zinc oxide (ZnO) thin film deposited by reactive high power impulse magnetron sputtering (R-HiPIMS) on glass substrates without external heating. We focus on the influence of deposition parameter, the ratio of O2/Ar exactly, on the crystalline and electrical properties of ZnO films. It is found that n-type ZnO film with a high carrier concentration can be grown through HiPIMS technique, the ratio of O2/Ar remarkably affects the ZnO crystalline and electrical properties. At O2/Ar = 14/80 sccm, the ZnO film was orientated at c-axis (002) plane. Based on the temporal resolution optical emission spectroscopy (OES), for the proposal of the correlation of film structure with plasma radicals and the reaction process in ZnO growth, the components in plasma are diagnosed. It is concluded that in a higher oxygen partial pressure, owing to the high ionization rate in HiPIMS, the oxide layer formed between pulses is removed, the growth of a new oxide layer during the pulse is hindered, hence the growth rate is increased, and the carrier concentration caused from point defects in ZnO film is high.

Magnetic properties and giant magneto-impedance effect in electroless-deposited CoP/Cu composite wires

The influence of deposition parameters on the structure and magnetic properties of CoP/Cu composite wires had been studied systematically in this paper. These parameters hold a significant effect on the surface topography, coating composition, deposition rate, magnetic properties and giant magnetoimpedance (GMI) effect of the composite wires. The CoP/Cu composite wire is layered clearly, the coating is uniform and the soft magnetic properties is excellent, the largest value of field sensitivity (ξ) is 195%/Oe and the maximum GMI ratio is 902%, which is the highest GMI value of the CoP composites materials so far. This result will be great significance for further study of the application of magnetic sensors.

Toward 3D Thin-Film Batteries: Optimal Current-Collector Design and Scalable Fabrication of TiO2 Thin-Film Electrodes

Three-dimensional (3D) thin-film solid-state batteries are an interesting concept for microstorage, promising high footprint capacity, fast charging, safety, and long lifetime. However, to realize their commercialization, several challenges still need to be overcome. In this work, we focus on two issues: the conformal coating and the high throughput deposition of thin-film layers. First, to facilitate conformal deposition, a design based on 3D micropillars is chosen. Although such a design has been suggested in the past, we calculate for the first time what (footprint) capacities can be expected when using fully optimized pillar geometries while taking practical manufacturability into consideration. Next, spatial atomic layer deposition (S-ALD) is investigated as a scalable and conformal deposition technique. As proof-of-concept, 100 nm Cl-doped am-TiO2 thin-film electrodes are deposited by S-ALD on TiN-coated silicon micropillars. The influence of deposition parameters (i.e., exposure time and temperature) on the conformality and uniformity across the micropillar substrate is investigated. The results are discussed in terms of precursor diffusion and depletion, which is supported by an analytical model developed for our micropillar array. Furthermore, the Li-ion insertion properties of 3D electrodes fabricated by S-ALD and conventional ALD are compared. This research highlights the challenges and promises of 3D microbatteries and guides future S-ALD development to enable conformal and high-throughput thin-film deposition.

Influence of deposition parameters on the structure and microstructure of Bi12TiO20 films obtained by pulsed laser deposition

The structure, morphology and surface roughness of Bi12TiO20 (BTO) thin films grown on R-sapphire by pulsed laser deposition (PLD) were studied at different substrate temperatures, target-substrate distances, oxygen pressures and laser-pulse repetition rates. Although the substrate temperature seems to be the most important experimental parameter, the gas pressure and the target–substrate distance played important role on the phase formed and film thickness, with a significant effect of the laser-pulse repetition rate on the films thickness and preferred orientation of the deposited film. Single-phase γ-Bi12TiO20 was obtained on substrates at 650 °C, while several BTO metastable phases were observed in films deposited on substrates at temperatures between 500 and 600 °C. By the first time, thin films of pure and textured δ-Bi12TiO20 were successfully growth on substrates at 450 °C. When annealed, all the films deposited at lower temperatures resulted in the thermodynamically stable γ-Bi12TiO20.

Synthesis of phase pure vanadium dioxide (VO2) thin film by reactive pulsed laser deposition

Thin films of phase pure VO2 (M1 phase) are deposited on thermally grown oxide (Si/SiO2) substrate by reactive pulsed laser deposition of vanadium metal target. The influence of deposition parameters is studied by varying oxygen partial pressure while keeping other parameters constant. A thin film obtained at 50 mTorr is found to be phase pure by XRD and Raman spectral studies. SEM and AFM studies show smooth morphology with a surface roughness of 3–5 nm. The quality of the thin film was further established by characterizing the 68 °C (TSMT) transition by 2–3 orders of jump in resistance and a 60% change in reflectivity with minimum hysteresis. This single step process of deposition would be a suitable method for fabricating devices for smart window and metamaterial applications.

Chromogenic MoO3 thin films: thermo-, photo-, and electrochromic response to working pressure variation in rf reactive magnetron sputtering

The thermochromic, photochromic, and electrochromic properties of molybdenum trioxide (MoO3) thin films were studied. MoO3 thin films were deposited by rf reactive magnetron sputtering and the influence of deposition parameters, i.e. O2/Ar gas ratio and working pressure, on the chromogenic properties was investigated. Thermochromism was induced by annealing the samples in either air or argon in the range 23–300 °C for 2 h. We found that the highest response was obtained for samples grown at 5.3 × 10−1 Pa, although films annealed in air showed a maximum coloration around 250 °C that became bleached above this temperature. As for the annealing in argon, the thermochromic effect increased even at 300 °C. By exposing samples to UV irradiation in air, photochromism could be induced for different intervals ranging from 0 to 3 h. The highest photochromic response was obtained for samples deposited at 1.3 Pa. Cyclic voltammetry for 20 cycles in a 1 M LiClO4 in propylene carbonate solution, inside a glovebox filled with argon, was used to evaluate the electrochromic response. Samples that showed optimum electrochromic response were deposited at 1.6 Pa. These results are explained in terms of the optical, structural, surface chemical composition, and vibrational modes.

Diamond-like carbon prepared by pulsed laser deposition with ion bombardment: physical properties

Diamond-like carbon (DLC) and titanium-doped DLC thin films were prepared by unique hybrid system consisting of pulsed laser deposition, ion source (bombardment) and magnetron sputtering. The influence of deposition parameters (ion energies, deposition pressures and magnetron power) on composition and physical properties was studied. Composition and sp3/sp2 ratio were determined by XPS. sp3/sp2 ratio was in the range from 1.4 to 2.2 for undoped DLC and from 3.4 to 4.8 for Ti-DLC. AFM showed that the layers were smooth, but with small amounts of random droplets. The measurements of the contact angle and determination of surface free energy were made for water, diiodomethane and ethylene glycol. Hardness and reduced Young’s modulus varied from 20 to 31 GPa and from 182 to 276 GPa, respectively. Film adhesion was determined by scratch test; LC3 reached 23 N for DLC and 27 N for TiDLC. Optimization of sp3/sp2 ratio, hardness and adhesion to biomedical alloys will advance the DLC coatings usability in the field of implantology.

Dynamics of faceted thin films formation during vapor deposition

In this study, an anisotropic phase-field model was established to simulate the growth of crystalline thin films during vapor deposition. The formation and evolution of characteristic surface with faceted morphologies were demonstrated, in accordance with the regularly obtained microstructure in the actual experiments. In addition, the influences of deposition parameters, such as the deposition rate and the interfacial energy, on the formation mechanism of the characteristic morphology were also illustrated. While a relatively low surface energy of substrate was regarded, the faceted islands were formed, owing to the anisotropic interfacial energy of thin films. In the condition of a high surface energy of substrate, the layered structures of deposited films were produced, which was corresponding to the Frank–van der Merwe growth mode. As various deposition rates were utilized in the numerical simulations, diverse surface morphologies were developed on the basis of the dominant mechanisms, correlating with the adatom diffusion and the deposition kinetics. According to the calculation results, it was observed that a surface character with flattened morphology was generally driven by the adatom diffusion, while the factor of the deposition kinetics was inclined to roughen the surface of thin films. These numerical simulations enhanced the knowledge of thin film growth and facilitated the progress of the vapor deposition technology for advanced applications.

Growth and properties of nanostructured titanium dioxide deposited by supersonic plasma jet deposition

Titanium dioxide (TiO2) is a wide gap semiconductor suitable for many applications. In this work, TiO2 nanostructured thin films are deposited by a plasma assisted supersonic deposition technique on silicon and on conductive glass substrates. Optical Emission Spectroscopy (OES) is used to monitor plasma conditions and precursor dissociation reactions. The influence of deposition parameters on TiO2 structure, uniformity, grain size, and optical properties are investigated by atomic force microscopy (AFM), mechanical profilometer, scanning electron microscopy (SEM) and spectroscopic ellipsometry (SE). Experimental results show how employed technique allows obtaining uniform films, with a tunable deposition range. Grains size could be chosen varying precursor flux during the deposition process. Films nanostructure and porosity result to be affected by grains size. Substrate roughness results to affect film morphology.

Study on defects in ZnS/YbF3 infrared coatings on silicon substrates

In order to reduce the numbers of defects, the influence of deposition parameters (i.e., deposition rate and substrate temperature) and deposition methods (i.e., thermal evaporation and electron beam evaporation) on the defect density of ZnS monolayer, YbF3 monolayer and ZnS/YbF3 multilayer coatings deposited on silicon substrates were investigated experimentally. The results show that deposition rate and substrate temperature have major influence on the defect density. For ZnS monolayer coatings, the optimum deposition rate is approximately 1.2nm/s, and the optimum substrate temperature is from 80°C to 120°C. Meanwhile, for YbF3 monolayer coatings, the optimum deposition rate is approximately 0.4nm/s, and the optimum substrate temperature is from 100°C to 150°C. Furthermore, the defect density of ZnS or YbF3 monolayer coatings deposited by thermal evaporation is much lower than that by electron beam evaporation. The defect density of ZnS/YbF3 multilayer coatings can be reduced significantly by optimizing the substrate temperature and deposition rate with the method of thermal evaporation.

Influence of electrochemical deposition parameters on capillary performance of a rectangular grooved wick with a porous layer

A wick is a key component of two-phase heat transfer devices. To balance conventional conflicting requirements between permeability and capillary pressure performance, a rectangular grooved composite wick combined with a porous deposition layer was fabricated on a copper plate using a combined technology of planing, electrochemical deposition and heat treatment. The permeability of this composite wick was tested experimentally by a forced liquid flow method to investigate the effect of electrochemical deposition parameters. Deposition current density was shown to affect permeability more intensely than deposition time. To overcome the difficulty of porosity measurement, a modified capillary performance parameter K/(AiwReff) instead of conventional K/Reff was proposed to evaluate the comprehensive capillary performance of the composite wick. In addition, an infrared (IR) thermal imaging method was employed to investigate capillary rising height and velocity, using ethanol as the test liquid. The influence of deposition parameters and wick types on the values of parameter K/(AiwReff) was discussed. The results show that there is an optimal value of both deposition time and current density to maximize capillary performance of the composite wick. Comparative studies show that a composite wick features a better capillary performance with proper fabrication parameters than a plane-deposition or its preformed smooth grooved wick.