Effect of ion-beam assisted deposition on the film stresses of TiO_2 and SiO_2 and stress control

Based on Hartmann-Shack sensor technique, an online thin film stress measuring system was introduced to measure the film stresses of TiO2 and SiO2, and comparison was made between the film stresses prepared respectively by the conventional process and the ion-beam assisted deposition. The effect of ion-beam assisted deposition on the film stresses of TiO2 and SiO2 was investigated in details, and the stress control methodologies using on-line adjustment and film doping were put forward. The results show that the film stress value of TiO2 prepared by ion-beam assisted deposition is 40 MPa lower than that prepared by conventional process, and the stress of TiO2 film changes gradually from tensile stress into compressive stress with increasing ion energy; while the film stress of SiO2 is a tensile stress under ion-beam assisted deposition because of the ion-beam sputtering effect, and the film refractive index decreases with increasing ion energy. A dynamic film stress control can be achieved through in-situ adjustment of the processing parameters based on the online film stress measuring technique, and the intrinsic stress of film can be effectively changed through film doping.

A New hcp Phase Formed in the Ni-Nb System during Ion-beam-assisted Deposition

The Ni80Nb20 films were prepared by ion beam assisted deposition (IBAD) with various Ar+ ion energies. A phase evolution of fcc→amorphous→Ni+Nb→Ni+hcp was observed with the increasing of ion beam energy from 2 keV to 8 keV. When bombarded by Ar+ ions of 8 keV during deposition, a new crystalline phase with hcp structure was obtained, of which the lattice parameters are a=0.286 nm and c=0.483 nm, different from those of the similar A3B-type hcp phase previously reported. The experimental results were discussed in terms of thermodynamics and restricted kinetic conditions in the far-from-equilibrium process of IBAD. The formation of hep phase may also be related to the valence electron effect.

CORROSION BEHAVIOR OF Cu-Nb AND Ni-Nb AMORPHOUS FILMS PREPARED BY ION BEAM ASSISTED DEPOSITION

The Cu25 Nb75 and Ni45Nb55 amorphous films with about 500nm thickness were prepared by ion beam assisted deposition (IBAD). Potentiodynamic polarization measurement was adopted to investigate the corrosion resistance of samples and the tests were carried out respectively in 1mol/L H2SO4 and NaOH aquatic solution. The corrosion performance of the amorphous films was compared with that of multilayered and pure Nb films. Experimental results indicated that the corrosion resistance of amorphous films was better than that of the corresponding multilayers and pure Nb films for both Ni-Nb system with negative heat of formation and Cu-Nb system with positive heat of formation.

Effects of SiO_2 and TiO_2 on resistance stabilities of flexible indium-tin-oxide films prepared by ion assisted deposition

Inorganic buffer layers such as SiO2 or TiO2 and transparent conductive indium-tin-oxide （ITO） films were prepared on polyethylene terephthalate （PET） substrates by ion assisted deposition （IAD） at room temperature, and the effects of SiO2 and TiOzon the bending resistance performance of flexible ITO films were investigated. The results show that ITO films with SiO2 or TiO2 buffer layer have better resistance stabilities compared to ones without the buffer layer when the ITO films are inwards bent at a bending radius more than 1.2 cm and when the ITO films are outwards bent at a bending radius from 0.8 cm to 1.2 cm. 1TO films with SiO2 buffer layer have better resistance sta- bilities compared to ones with TiO2 buffer layer after the ITO fdms are bent several hundreds of cycles at the same bending radius, for the adhesion of SiO2 is stronger than that of TiO2. The compressive stress resulted from inward bending leads to the formation of more defects in the ITO films compared with the tensile stress arising from outward bending. SiO2 and TiO2 buffer layers can effectively improve the crystallinity of ITO films in （400）, （440） directions.

AMORPHIZATION IN Nb-M (M=Fe, Co, Ni) BINARY METAL SYSTEMS INDUCED BY ION BEAM ASSISTED DEPOSITION (IBAD)

Ion beam assisted deposition technique (IBAD) was utilized to systematically study amorphization in binary metal systems of Nb-magnetic element, i.e., Nb-M (M=Fe, Co or Ni). The glass forming range termed as Nb fraction of Nb-Fe system was about 34at.% to 56at.%, that of Nb-Co system was about 32at.% to 72at.% and that of Nb-Ni about 20at. % to 80at. %. Similar percolation patterns were found in amorphous alloy films. The fractal dimensions of the percolation patterns approach to 2, which indicates 2-D layer growth for amorphous phases. It is regarded that the assisted Ar+ ion beam during the deposition process plays important role for the 2-D layer growth. Some metastable crystalline phases were obtained in these three systems by IBAD, e.g., bcc supersaturated solid solutions in Nb-Fe and Nb-Co systems, fcc and hcp phases in Nb-Co and Nb-Ni systems. The formation and competing between the amorphous and the metastable crystalline phases were determined by both the phases' thermodynamic states in binary metal systems and kinetics during IBAD process.

Tribological Properties of DLC Film Prepared by C^+ Ion Beam-assisted Deposition (IBAD)

C ^＋ ion beam-assisted deposition was utilized to prepare deposit diamond-like carbon （ DLC ） film. With the help of a series of experiments such as Raman spectroscopy, FT-IR spectroscopy, AFM and nanoindentation , the DLC film has been recognized as hydrogenated DLC film and its tribologicul properties have been evaluated. The bull-on-disc testing results show that the hardness and the tribologicul properties of the DLC film produced by C^ ＋ ion beam- assisted deposition are improved significantly. DLC film produced by C ^＋ ion beam- assisted deposition is positive to have a prosperous tribologicul application in the near future.

Giant efficiency and color purity enhancement in multicolor inorganic perovskite light-emitting diodes via heating-assisted vacuum deposition

Inorganic perovskites(Cs Pb X3(X=I,Br,Cl))have broad prospection in the field of high-definition displaying due to its excellent optoelectronic characteristics.The vacuum deposition process possesses advantages and competitiveness in the industrialized production.However,the performance of light emitting diodes(LEDs)based on vacuum-deposited is incredibly low.Herein,we proposed a heating-assisted vacuum deposition(HAVD)method to construct inorganic perovskite LEDs(Pe LEDs)with enhanced performance.The roughness and crystallinity of perovskite film were improved by regulating the heating treatment of substrates.And the perovskite film exhibited largely rise in luminescence,with decreasing defect density.Consequently,with the optimized temperature,the green Pe LEDs exhibited 100-fold improvement of external quantum efficiency(EQE)with the luminance of up to 11941 cd/m2,and the full width at half-maximum(FWHM)of the electroluminescence(EL)spectra was decreased from 25 to 17 nm.At the same time,the red and blue Pe LEDs also exhibited obvious enhancement in EQE and luminance by HAVD method,and both the FWHM of EL spectra dropped below 20 nm,exhibiting excellent high color purity.HAVD strategy has a huge potential to be a new commonly used method for low-cost fabrication of displays and lighting.

Characteristics and properties of metal aluminum thin films prepared by electron cyclotron resonance plasma-assisted atomic layer deposition technology

Metal aluminum （A1） thin films are prepared by 2450 MHz electron cyclotron resonance plasma-assisted atomic layer deposition on glass and p-Si substrates using trimethylaluminum as the precursor and hydrogen as the reductive gas. We focus our attention on the plasma source for the thin-film preparation and annealing of the as-deposited films relative to the surface square resistivity. The square resistivity of as-deposited A1 films is greatly reduced after annealing and almost reaches the value of bulk metal. Through chemical and structural analysis, we conclude that the square resistivity is determined by neither the contaminant concentration nor the surface morphology, but by both the crystallinity and crystal size in this process.

Structural Evolution of SiC Films During Plasma-Assisted Chemical Vapour Deposition

Evolution of chemical bonding configurations for the films deposited from hexam- ethyldisiloxane （HMDSO） diluted with H2 during plasma assisted chemical vapour deposition is investigated. In the experiment a small amount of CH4 was added to adjust the plasma environment and modify the structure of the deposited films. The measurements of Raman spectroscopy and X-ray diffraction （XRD） revealed the production of 6H-SiC embedded in the amorphous matrix without the input of CH4. As CH4 was introduced into the deposition reaction, the transition of 6H-SiC to cubic SiC in the films took place, and also the film surfaces changed from a structure of ellipsoids to cauliflower-like shapes. With a further increase of CH4 in the flow ratio, the obtained films varied from Si-C bonding dominant to a sp^2/sp^3 carbon-rich composition.

Cr/CrN Compound Films Prepared by Ion Beam Assisted Deposition for Improving the Performance of Bearing Steel

With the development of industry, much attention has been paid to lengthening the life span of bearings. As reported in this paper, we investigated the Cr/CrN compound films formed on the specimens of W9Cr4V2Mo bearing steel by ion beam assisted deposition for improving the performance of bearing steels. The Vicker＇s microhardness, pin-on-disc, electrochemical measurement, XRD and SEM tests were used to characterize and analyze the treated samples. All results indicated that the mechanical properties of the treated samples were good, with the microhardness greater than that of the uncoated specimen, and the wear resistance, the passivity and pitting corrosion resistance increased considerably, the films possessed alternate Cr and CrN compound phases and produced different effects on the improvement of the performance of W9Cr4V2Mo bearing steels with different composing phases.

PREPARATION OF B-N FILMS BY ION BEAM ASSISTED DEPOSITION

BN films,synthesized by ion beam assisted deposition,were analysed by RBS,AES, IR spectra and TEM.Formatiom of c-BN phase was shown not only by IR spectra at absorption peak of 1100 cm^(-1),but also by electron diffraction pattern.The results of AES demonstrate an effect of N^+ implantation near the film surface.The deposited films consist of three layers,i.e.,ion implantation layer,film layer and mixed intermediatelayer, according to the difference of concentration.The micro-Knoop hardness of the film is 25—35 GPa.

Low-Temperature Soft-Cover-Assisted Hydrolysis Deposition of Large-Scale TiO_2 Layer for Efficient Perovskite Solar Modules

Perovskite solar cells with TiO_2 electron transport layers exhibit power conversion efficiency(PCE) as high as 22.7% in single cells. However, the preparation process of the TiO_2 layer is adopted by an unscalable method or requires high-temperature sintering, which precludes its potential use for mass production of flexible devices. In this study, a scalable low-temperature softcover-assisted hydrolysis(SAH) method is presented,where the precursor solution is sandwiched between a soft cover and preheated substrate to form a closed hydrolysis environment. Compact homogeneous TiO_2 films with a needle-like structure were obtained after the hydrolysis of a TiCl_4 aqueous solution. Moreover, by careful optimization of the TiO_2 fabrication conditions, a high PCE of 14.01% could be achieved for a solar module(4 × 4 cm^2) prepared using the SAH method. This method provides a novel approach for the efficient scale-up of the low-temperature TiO_2 film growth for industrial applications.

Monte Carlo Simulation of Electron Velocity Distribution and Gas Phase Process in Electron-Assisted Chemical Vapor Deposition

The gas phase process of diamond film deposition from CH4/H2 gas mixture by electron-assisted chemical vapor deposition is simulated by the Monte-Carlo method. The electron velocity distribution under different E/P (the ratio of the electric field to gas pressure) is obtained, and the velocity profile is asymmetric. The variation of the number density of CH3 and H with different CH4 concentrations and gas pressure is investigated, and the optimal experimental parameters are obtained: the gas pressure is in the range of 2.5 kPa - 15 kPa and the CH4 concentration is in the range of 0.5% - 1%. The energy carried by the fragment CH3 as the function of the experiment parameters is investigated to explain the diamond growth at low temperature. These results will be helpful to the selection of optimum experimental conditions for high quality diamond films deposition in EACVD and the modeling of plasma chemical vapor deposition.

Improvement of Surface Morphology of Yttrium-Stabilized Zirconia Films Deposited by Pulsed Laser Deposition on Rolling Assisted Biaxially Textured Substrate Tapes

The surface morphology of buffer layer yttrium-stabilized zirconia （YSZ） of YBa2CuaO7-σ （YBCO） high temperature superconducting films relies on a series of controllable experimental parameters. In this work, we focus on the influence of pulsed laser frequency and target crystalline type on surface morphology of YSZ films deposited by pulsed laser deposition （PLD） on rolling assisted biaxially textured substrate tapes. Usually two kinds of particles are observed in the YSZ layer： randomly distributed ones on the whole film and self-assembled ones along grain boundaries. SEM images are used to prove that particles can be partly removed when choosing dense targets of single crystalline. Lower frequency of pulsed laser also contributes to a smoother film surface. TEM images are used to view the crystalline structure of thin film. Thus we can obtain a basic understanding of how to prepare a particle-free YSZ buffer layer for YBCO in optimized conditions using PLD. The YBCO layer with nice structure and critical current density of around 5 MA/cm2 can be reached on smooth YSZ samples.

Structural Characterization of Thin Epitaxial GaN Films on Polymer Polyimides Substrates by Ion Beam Assisted Deposition

The Epitaxial GaN thin films have been fabricated by Ion Beam Assisted Deposition (IBAD) process using nitrogen ions with hyperthermal energies on the polyimides polymer substrates. By applying with the Reflection of High-Energy Electron Diffraction (RHEED), Scanning Electron Microscopy (SEM) and Quantum Design Physical Properties Measurement System, the behaviour of hexagonal GaN thin films is investigated. The result showed that the high quality of the deposited GaN layers kept appearing for many parameters depending on the temperature greatly. The behaviour of high quality of epitaxial GaN coating on the polyimide polymer substrates is a promising material for optoelectronic devices and semiconductor devices application.

Tuning the Spatially Controlled Growth,Structural Self-Organizing and Cluster-Assembling of the Carbyne-Enriched Nano-Matrix during Ion-Assisted Pulse-Plasma Deposition

Carbyne-enriched nanomaterials are of current interest in nanotechnology-related applications.The properties of these nanomaterials greatly depend on their production process.In particular,structural self-organization and auto-synchronization of nanostructures are typical phenomena observed during the growth and heteroatom-doping of carbyne-enriched nanostructured metamaterials by the ion-assisted pulse-plasma deposition method.Accordingly,fine tuning of these processes may be seen as the key step to the predictive designing of carbyneenriched nano-matrices with improved properties.In particular,we propose an innovative concept,connected with application of the vibrational-acoustic effects and based on universal Cymatics mechanisms.These effects are used to induce vibration-assisted self-organized wave patterns together with the simultaneous manipulation of their properties through an electric field.Interaction between the inhomogeneous electric field distribution generated on the vibrating layer and the plasma ions serves as the additional energizing factor controlling the local pattern formation and self-organization of the nano-structures.

A Study on Biocompatibility of TiN Thin Film Deposited on 317L Stainless Steel by Ion Beam Assisted Deposition

Titanium nitride ceramic thin films on 317L stainless steel(SS317L) substrate were deposited by Ion Beam Assisted Deposition (IBAD). The composition of the TiN films were investigated by Auger electron spectroscopy(AES), while the preferential orientation of the deposited film and phase composition were determined by X-ray diffraction(XRD). Adhesion was measured through Micro Scratch Tester(MST), and the corrosion resistance was evaluated by the electrochemical corrosion experiments in Hamk’s simulated human plasma. Specially, the biocompatibility of SS317L and TiN thin films were studied with fibroblast and marrow cell cultures in vitro. The results show that TiN thin films deposited on SS317L by means of IBAD can make remarkable changes on the structure and properties of the surface. At 37℃ Hank’s simulated plasma, free corrosion potential (E corr ) and breakthrough potential of pitting corrosion (E b) were both improved by coating TiN films . The culture results show that ion beam assisted TiN coatings exhibit a higher degree of cytocompatibility than that of SS317L and the cells grow better on those proper rough surfaces.

Synthesis, properties, and applications of large-scale two-dimensional materials by polymer-assisted deposition

Two-dimensional(2D) materials have attracted considerable attention because of their novel and tunable electronic,optical, ferromagnetic, and chemical properties. Compared to mechanical exfoliation and chemical vapor deposition, polymer-assisted deposition(PAD) is more suitable for mass production of 2D materials owing to its good reproducibility and reliability. In this review, we summarize the recent development of PAD on syntheses of 2D materials. First, we introduce principles and processing steps of PAD. Second, 2D materials, including graphene, MoS2, and MoS2/glassy-graphene heterostructures, are presented to illustrate the power of PAD and provide readers with the opportunity to assess the method. Last, we discuss the future prospects and challenges in this research field. This review provides a novel technique for preparing 2D layered materials and may inspire new applications of 2D layered materials.

The Effects of Annealing and Discharging on the Characteristics of MgO Thin Films Prepared by Ion Beam-Assisted Deposition as a Protective Layer of AC-PDP

This study investigated the effects of annealing and discharging on the characteristics of MgO thin films prepared by ion beam-assisted deposition as a protective layer of AC-PDP. By an annealing process at a temperature of 450 ℃ for more than three hours, the crystallinity of the deposited MgO films was improved, but the surface of the （200）-oriented MgO thin films in the vicinity of the discharge electrodes, especially on the inner sides of the electrodes, was subjected to crack formation to the compressive stress of The failure mechanism of the MgO films plus the additional （200）-oriented MgO films was due compressive stress induced by the differences in the coefficient of thermal expansion between the electrode and the dielectric layer. In the discharging process, all MgO films were eroded unevenly, and the serious erosion occurred near the edges of the discharge electrodes. ATM（atomic force microscopy） images show that the eroded surface of the （200）-oriented MgO thin film is smoother than that of the （111）-oriented fihn. Also, the （200）-oriented MgO thin film shows an improved ability to resist ion erosion compared to the （111）-oriented film.

Morphology Simulation for Ion-Assisted Deposition Process

The molecular dynamics simulation is applied to investigate the influence of the incident ion energy and incident angular distribution upon ion-assisted deposition process. The Cu-Cu and Ar-Cu interactions are modeled using the many body tight-binding potential and the Moliere potential, respectively, and the interface width is used to characterize the surface roughness properties at both transient and final state conditions. The results show that the surface roughness of the deposition film is lower when more Ar-to-Cu ratio is used at the same incident energy and angle. For the relative low or high incident energy, the film morphologies are not sensitive to the incident angle. However, if the incident energy of the argon ions is too high, the film morphology will be worse than that without using the ion-assisted deposition.