Ion Beam Sputter Deposition Method Research Articles

Paper-based immunosensor integrated with bioinspired Cu-polydopamine nanozyme for voltammetric detection of CA-15-3 tumor marker

This manuscript describes the fabrication and characterization of a highly conductive paper-based nanoplatform for immobliztion of anti-CA 15-3 antibodies. For this purpose, cellulosic filter paper (FP) was first coated with Cu nanosponges (CuNSs) through ion beam sputtering deposition (IBSD) method and then covered with Cu-doped polydopamine nanospheres (Cu-PDA). Polydopamine doped with copper exhibited laccase (multi-copper oxidase)-mimicking properties. Bioinspired by the structure of the active site and the electron transfer mechanism of laccase, Cu-PDA nanozyme catalyzed the oxidation of hydroquinone (HQ) signal probe. In this design, CA-15-3, a prognostic biomarker in the breast cancer, was chosen as a model target. To the best of our knowledge, this is the only paper on the design of an electrochemical biosensor based on dense and uniform CuNSs produced by IBSD. More importantly, Cu-PDA is biocompatible and biodegradable, which makes it a potential competitor in the point-of-care (POC) biosensing applications. Thus, this paper-based sensing strategy can be used in designing cost-effective flexible chips consisting of electrodes printed on paper for in-situ and real-time monitoring biomarkers under clinical conditions. In addition to these outstanding features, the LOD (1.3 mU mL 1) and LOQ (4.3 mU mL 1) of the Ab/HQ/Cu-PDA/CuNSs/FP-based immunosensor was significantly lower than the clinically relevant cut-off level (30 U mL 1). In the practical applications, one of the key superiorities of this immuosensor is the wide DLR (5 mU mL 1–280 U mL 1) which covers the ultimate value of healthy and patient individuals.

A sensing strategy based on aptamers alkylated with melphalan and graphite nanocrystals in a bed of tetrahedral amorphous carbon for electrochemical detection of lead ions in human urine

We report a voltammetric aptasensor based on the graphite nanocrystals in a bed of tetrahedral amorphous carbon (GNC-TAC) and guanine (G)-rich aptamers alkylated with melphalan anticancer for determination of ultratrace Pb2+ in the clinical samples. In this work, an adhesive and stable layer of GNC-TAC was formed on the cellulose paper by the ion beam sputtering deposition (IBSD) method. This porous conductive nanographite film plays a key role in providing a large area for adsorption of ferrocene carboxylic acid (FC-COOH) anticancer as a redox indicator. Then, melphalan that attaches the alkyl groups to the guanine bases of DNA aptamer was bonded covalently to the carboxylic groups of FC-COOH via the aid of EDC/NHS. The introduction of Pb2+ ions to the aptamer/melphalan/FC-COOH/GNC-TAC/paper electrode leads to the formation of a G-quadruplex (G4)/Pb2+ complex and dissociation of this complex from the modified electrode surface. The target-induced aptamer release from melphalan/FC-COOH/GNC-TAC/paper electrode makes the sensing interface smaller which results in an increase in the current signal. Based on this signal-on mechanism, the sensitive detection of Pb2+ ions in the dynamic linear range (DLR) of 0.5–700.0 μg L−1 is realized (limit of detection (LOD): 0.15 μg L−1). The present strategy shows remarkable advantages including high selectivity and wide detectable range. More importantly, the good consistency of the results obtained with the aptasensor and those by the quality control material (QCM) analysis and atomic absorption spectroscopy equipped with graphite furnace (GF-AAS) technique showed that the proposed strategy has a high potential for Pb2+ detection in the clinical samples.

Band alignment of h-BN/β-Ga2O3 heterostructure grown via ion beam sputtering deposition

Integrating two-dimensional ultra-wide band gap hexagonal boron nitride (h-BN) on β-Ga2O3 surface into van der Waals heterostructures is of great interest for developing novel high-power devices and optoelectronic devices because of their unique properties. The energy band alignment at the heterointerface is critical for device design, however, the band alignment of h-BN/β-Ga2O3 heterojunction has not been investigated to date. In this work, the h-BN/β-Ga2O3 heterostructure is constructed by directly growing h-BN few-layer on the β-Ga2O3 single crystal substrate using ion beam sputtering deposition method. The high-quality few-layer h-BN with the abrupt interface and smooth surface allow for the accurate determination of band alignment at the h-BN/β-Ga2O3 heterointerface by X-ray photoelectron spectroscopies. The valence and conduction band offsets are determined to be 0.47 and 1.42 eV for the h-BN/β-Ga2O3 heterostructure, respectively, with a type-Ⅱ staggered band alignment. Furthermore, the electronic structures of h-BN/β-Ga2O3 heterostructure are also investigated experimentally and theoretically. These results indicate that the h-BN/β-Ga2O3 heterostructure has great potential in (opto)electronic devices.

Application of titanium dioxide barrier layers for the ferromagnetic/ferroelectric multiferroics formation

The layered multiferroics Co/PZT were obtained by ion-beam sputtering-deposition method, where PZT is a ferroelectric ceramic based on lead titanate zirconate of the composition PbZr0.45Ti0.55O3 with a thermostable plane-parallel ferroelectric/ferromagnet interface. Using cross-sectional scanning electron microscopy (SEM), we studied the interface of a cobalt layer up to several micrometers thick with a thick ceramic substrate of lead zirconate titanate. It has been shown that the use of a titanium dioxide barrier layer of TiO2 instead of PZT allows quality improvement of the interface by reducing the duration of ion-beam planarization of the ferroelectric substrate, and also to eliminate the formation of intermediate chemical compounds. Based on the data of X-ray phase analysis (XRD), it was concluded that the TiO2 layer is amorphous. Magnetoelectric measurements have shown that the use of titanium dioxide instead of PZT under appropriate planarization modes can increase the low-frequency magnetoelectric effect to 5 mV/(cm∙Ое), compared with structures with a sputtering planarizing layer of PZT, where the magnitude of the low-frequency magnetoelectric effect is 2 mV/(cm∙Оe). These results allow us to improve the characteristics of these structures when used as sensitive elements in devices for formation – processing of information and magnetic field sensors based on the magnetoelectric effect.

Origin and effect of film sub-stoichiometry on ultraviolet, ns-laser damage resistance of hafnia single layers

Understanding the origin of laser damage-prone precursors in high index materials such as hafnia holds the key to the development of laser damage-resistant multilayer dielectric coated optics for high power and energy laser systems. In this study, we investigate the source of sub-stoichiometry, a potent laser damage precursor, in hafnia films produced by an ion beam sputtering (IBS) deposition method and the effect of such defects on the film performance upon ns ultraviolet (UV) laser (8 ns, 355 nm) exposure. Chemical analysis of data obtained via Rutherford backscattering spectroscopy (RBS) suggests that hafnia films deposited at two different planetary locations from the same deposition run exhibit anisotropic and location-dependent stoichiometries. While the oxygen-to-hafnium ratio is at the stoichiometric value of 2 for the hafnia film at the edge location, the ratio is significantly deviated and is 1.7 for that deposited at the planetary center. The sub-stoichiometric hafnia films display a much lower 1-on-1 damage onset at 1.6 ± 0.2 J/cm2 compared to 2.3 ± 0.2 J/cm2 in a stoichiometric film. The low damage performance films also have an over three times higher damage density at fluences above initiation. Coupled with Monte Carlo simulations, we reveal that sub-stoichiometry is primarily attributed to preferential removal of oxygen during film deposition by the bombardment of energetic reflected argon neutrals. The resulting oxygen deficiencies create the sub-bandgap states which facilitate the strong laser energy coupling and reduce the resistance to laser-induced damage in the hafnia single layer films.

Effect of Irradiation Atmospheres on the Film Growth of Iron Oxide on Si Substrate by Ion Beam Sputter Deposition Method

Effect of Irradiation Atmospheres on the Film Growth of Iron Oxide on Si Substrate by Ion Beam Sputter Deposition Method

Double-Lattice Magnetoplasmonic Structures Based on BIG and Perforated Gold Films

A method of manufacturing double-lattice magnetoplasmonic crystals with the structure (Au/BIG)2, in which the plasmon gold lattices are displaced relative to each other by half a period, has been presented. Gold films with thicknesses of about 40 nm have been formed by the ion-beam sputtering–deposition method, while the adhesive properties of the films allow the dimensional etching by a sharp-focused ion beam. It has been shown that the formation of the second plasmon lattice located on top of the 100 nm thick garnet layer allows the preserving of the periodicity of the first Au lattice. However, there is a significant influence of diffusion spreading on the lower lattice material, which leads to a decrease in its density. The dependence of the intensity magnetooptical effect in the geometry on the transmission as a function of the thickness of the upper lattice and presence of an additional layer of Ta2O5 has been studied.

AMORPHIZATION OF CERIUM MONONITRIDE DURING OXIDIZATION CHARACTERIZED BY OPTICAL MICROSCOPY, SCANNING ELECTRON MICROSCOPY, X-RAY DIFFRACTION AND X-RAY PHOTOELECTRON SPECTROSCOPY

Cerium mononitride (CeN) film was fabricated by dual ion beam sputtering deposition method on silicon wafer. The oxidization process of CeN film was monitored by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The results showed that, when the CeN film was exposed to ambient atmosphere, bubbles appeared on the film surface rapidly and then the surface flaked off to powders. Meanwhile, the CeN film changed from polycrystalline to amorphous. XPS analysis indicated that the CeN was oxidized to Ce2O3 initially, and then further oxidized to CeO2. These results indicated that the CeN film degraded easily in ambient atmosphere, exhibiting little or no passivation.

The thermoelectric properties of zinc antimonide thin films fabricated through single element composite target

Zinc‑antimony binary system is an intermediate temperature thermoelectric material with great development prospects. In this work, Zn target and Sb target were jointed to form a composite target which was used for preparing zinc antimonide thin films by ion beam sputtering deposition method. When the target was combined by Zn and Sb strips following 1/1 cycle, and the thin films were annealed at 275 °C, 300 °C, 325 °C, 350 °C and 375 °C separately, the main component of the films is ZnSb. The test results show that certain annealing temperature is conducive to the crystallization of the film. The maximum power factor of 0.4 Wm−1 K−2 was achieved at 275 °C when the thin film annealed at 375 °C. When the target was combined by Zn and Sb strips following 1/1/2/1 cycle, the film (T1) has main Zn4Sb3 phase and be rich in Zn. The composition of the film can be regulated by controlling the content of elements in the target.

Optical properties of HfOx (x < 2) films grown by ion beam sputtering-deposition method

The optical properties of the HfOx films of different chemical composition (x ≤ 2) deposited by ion beam sputtering-deposition (IBSD) method were studied. Spectral dependencies of refractive index n(λ) and extinction coefficient k(λ) were determined with ellipsometry in λ = 250–1100 nm wavelength region. The x values (i.e. [O]/[Hf] ratio) for the films were derived from x-ray photoelectron spectroscopy (XPS) data. The spectral dependences of optical constants n(λ) and k(λ) were found to undergo radical changes with x = 1.78–1.82. The films with x < 1.78 demonstrated high extinction coefficient k > 1 with the metallic-like behavior of optical constants spectral dependences. The films with x > 1.82 were found to be transparent, with k = 0 and n(λ) being well approximated by a Cauchy polynomial dependence for dielectrics. Using a sample with a gradient of x, it was established that the transition from the metallic to the dielectric-like behavior of the optical constants occurs not smoothly, but is discontinuous. A sharp jump in the optical constants is observed at x ≈ 1.8. According to XPS data, the transparent films were found to consist of two components only: HfO2 and Hf4O7 suboxide. Cauchy polynomial coefficients for Hf4O7 suboxide and HfO2 were found by using the Bruggeman effective medium approximation.

Deposition of thin tungsten carbide films by dual ion beam sputtering deposition

Hard materials coating fabricated by physical vapor deposition techniques methods are wildly used because of their excellent mechanical strength, stability and chemical resistivity. In this article, compact and high Young's modulus tungsten carbide films with ∼100 nm thickness were prepared on Si (100) substrates by dual ion beam sputtering deposition method, and elucidates the influence of deposition temperature and assistant ion source on the adhesion strength and Young's modulus of tungsten carbide thin films. Morphological analysis, composition, and structure of tungsten carbide films were investigated by Atomic force microscope, X-ray photoelectron spectrometry, Scanning electron microscope. The X-ray diffraction analysis shows that the thin films comprise of hexagonal structure W2C. The adhesion strength is improved due to ion beam source bombardment and elevated deposition temperature. The Young's modulus of the film is codetermined by the density, microstructure and crystal structure. The influence of density, microstructure and crystal structure on Young's modulus was discussed in detail. The Young's modulus is improved due to the more compact structure caused by appropriate assistant source bombardment and elevated deposition temperature, and gets degradative due to the disorganized, coarse and granular structure caused by overlarge assistant source bombardment.

Phase control and Young’s modulus of tungsten thin film prepared by dual ion beam sputtering deposition

In this letter, tungsten films of varying thickness from ∼20 nm to ∼80 nm were prepared at different deposition temperature by Dual ion beam sputtering deposition (DIBSD) method. The influence of thickness and deposition temperature on the films phase, microstructure and Young’s modulus was studied briefly. The experiments prove that a double-layer structure, formation takes place i.e. β phase tungsten layer (low crystallinity) forms adjacent to the substrate and α tungsten phase layer (high crystallinity) forms above β phase. The increase in both the thickness and deposition temperature promotes the transformation from β phase to α phase which initiates from the interface between two phases. There is a critical thickness of ∼20 nm below which the film is a pure β phase, and the minimum thickness of forming pure α phase is affected by the deposition temperature, with 74 nm at 450°C, and 58 nm at 600°C. Furthermore, the decrease Young’s modulus of the tungsten film is ascribed to the formation of β phase which possesses low crystallinity with low density.

The atomic structure and chemical composition of HfOx (x < 2) films prepared by ion-beam sputtering deposition

Non-stoichiometric HfOx films of different chemical composition (x < 2) were fabricated by ion-beam sputtering deposition (IBSD) at room temperature. The ratio of O and Hf atoms in films x was varied by setting the O2 partial pressure in a chamber. An effect of chemical composition on the atomic structure of the films was studied by reflection high-energy electron diffraction, x-ray photoelectron spectroscopy and field emission scanning electron microscopy methods. The films were found to be amorphous, consisting only of three components: Hf-metal clusters, Hf4O7 suboxide and stoichiometric HfO2. The relative concentration of these components varies with changing x. The surface of the films contains the increased oxygen content compared to the bulk. It was found that the Hf4O7 suboxide concentration is maximal at x = 1.8. The concept of hafnium oxide film growth by the IBSD method is proposed to explain the lack of suboxides variety in the films and the instability of HfO2, when annealed at high temperature.

Ultrafast phase change and long durability of BN-incorporated GeSbTe

BN-incorporated amorphous Ge2Sb2Te5 (GST) films were deposited by an ion beam sputtering deposition method. The power-time-effect (PTE) diagrams showed that as the amount of BN increased, the crystallization temperature and phase change speed increased.

The structural transition from epitaxial Fe/Pt multilayers to an ordered FePt film using low energy ion beam sputtering deposition with no buffer layer

An epitaxial L10 FePt thin film grown from an [Fe(10Å)/Pt(10Å)]15 multilayer with the orientation of (001) was prepared by an ion beam sputtering deposition method without buffer layer. From the measurement data of X-ray diffraction and X-ray reflectivity, the multilayer structure was totally disappeared and a uniform FePt alloy thin film was formed at temperatures higher than 600°C. For the as-deposited thin film grown at 100°C, the multilayer already possesses an epitaxial structure. The epitaxial relation is FePt(001)[100]//MgO(001)[100] and this epitaxial relation persists after sequential high temperature annealing. An epitaxial L10 ordered FePt(001) film with order parameter of 0.95 was obtained when the annealing temperature reached 650°C. The ordered FePt(001) thin film has a perpendicular magnetic anisotropy with a squareness of 0.95±0.03 on the magnetic hysteresis loop. This experiment demonstrates that the low energy ion beam sputtering deposition will preserve the epitaxial relation with no buffer layer between multilayer and substrate.

Structural, magnetic and magnetoelectric studies of BaTiO3:Co nanocomposite films formed by ion-beam methods

Thin-film samples of ferroelectric barium titanate (BaTiO3) with cobalt nanoparticles were obtained by using either ion implantation or ion beam sputtering deposition (IBSD) techniques. The samples were characterized using X-ray diffraction, transmission electron microscopy, magnetometry and ferromagnetic resonance to investigate the efficiency of above ion-beam methods in the synthesis of magnetoelectric nanocomposite materials. Our structural studies show that high-fluence implantation with Co+ ions results in the formation of cobalt nanoparticles with mean size of 5nm in thin surface layer of monocrystalline plate of BaTiO3. On the other hand, larger nanoparticles of cobalt with sizes from 5 up to 40nm are formed in polycrystalline BaTiO3 matrix only after high-temperature annealing of BaTiO3:Co composite film prepared by IBSD method. Both types of thin-film nanocomposite samples have similar magnetic hysteresis curves in the sample plane. However Co-implanted BaTiO3 reveals strong uniaxial magnetic anisotropy for out-of-plane orientation, while BaTiO3:Co nanocomposite film demonstrates almost isotropic magnetic response. Strong magnetoelectric effect are observed in Co-implanted BaTiO3, and no magnetoelectric coupling are detected in BaTiO3:Co nanocomposite film formed by IBSD with subsequent high-temperature annealing.

Optimization of substrate pretreatment and deposition conditions for epitaxial growth of β‐FeSi2 film on Si(100)

AbstractEffect of substrate treatment conditions, deposition temperature and deposition rate on the crystallinity of β‐FeSi2 films formed on Si substrate was investigated. The substrates were treated with Ne+ ion beams at room temperature and then annealed at 1073 K prior to film fabrication by means of ion beam sputter deposition (IBSD) method. Combinations of experimental parameters which promote the film growth with an epitaxial relationship of β‐FeSi2 (100) // Si (100) were identified. These results were explained qualitatively in terms of the substrate treatment conditions, deposition temperature, as well as on the local Fe/Si ratio. The observed dependence of the film structure on these experimental parameters indicated that careful optimization of substrate treatment conditions and deposition parameters would further stimulate effort to fabricate β‐FeSi2 films with excellent crystalline properties. (© 2013 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Optoelectronic Properties of Nanostructured ZnO Thin Films Prepared on Glass and Transparent Flexible Clay Substrates by Hydrothermal Method

In the present work, transparent flexible polymer-doped clay (P-clay) substrates were successfully prepared for flexible hybrid organic–inorganic light emitting diode (HyLED) applications. The thermogravimetric–differential thermal analysis (TG–DTA) curves showed that the thermal resistance of P-clay film was higher than that of plastic substrates. Then indium doped tin oxide (ITO) thin films were prepared on newly fabricated P-clay substrates by ion-beam sputter deposition (IBSD) method. The as-prepared ITO/P-clay samples were annealed at 220 °C for 1 h. The optical transparency and electrical conductivity of annealed ITO film on P-clay with smooth surface were better than that of P-clay with rough surface. ZnO seed layers were prepared on annealed ITO/P-clay, ITO/glass, and clay substrates by IBSD method. Surface morphology study showed that the ZnO seed layer coated ITO/P-clay substrate with smooth surface was very suitable for growing vertically aligned ZnO nanorod arrays. The structural study showed that the ZnO nanorod arrays grown by low-temperature solution growth method have good crystallinity and high purity. Optical study showed that the as-prepared ZnO nanorod arrays have excellent optical properties.

Fabrication and Characterization of Flexible Organic Light Emitting Diodes Based on Transparent Flexible Clay Substrates

In the present work, transparent flexible polymer-doped clay (P-clay) substrates were prepared for flexible organic light emitting diode (OLED) applications. Nanocrystalline indium tin oxide (ITO) thin films were prepared on P-clay substrates by ion-beam sputter deposition method. The structural, optical, and electrical properties of as-prepared ITO/P-clay showed that the as-prepared ITO thin film was amorphous, and the average optical transparency and sheet resistance were around 84% and 56 Ω/□, respectively. The as-prepared ITO/P-clay samples were annealed at 200 and 270 °C for 1 h to improve the optical transparency and electrical conductivity. The average optical transparency was found to be maximum at an annealing temperature of 200 °C. Finally, N,N-bis[(1-naphthyl)-N,N '-diphenyl]-1,1'-biphenyl)-4,4'-diamine (NPB), tris(8-hydroxyquinoline) aluminum (Alq3) thin films, and aluminum (Al) electrode were prepared on ITO/P-clay substrates by thermal evaporation method. The current density–voltage (J–V) characteristic of Al/NPB/ITO/P-clay showed linear Ohmic behaviour. In contrast, J–V characteristic of Al/Alq3/NPB/ITO/P-clay showed non-linear Schottky behaviour. Finally, a very flexible OLED was successfully fabricated on newly fabricated transparent flexible P-clay substrates. The electroluminescence study showed that the emission intensity of light from the flexible OLED device gradually increased with increasing applied voltage.

Preparation and characterization of epitaxial growth of ZnO nanotip arrays by hydrothermal method

Preparation and characterization of epitaxial growth of ZnO nanotip arrays are essential for field emission applications due to its high emission rate of electron and fast electron-transfer rate. At first, nanocrystalline ITO thin films were prepared on glass substrates by ion-beam sputter deposition (IBSD) method. ZnO seed layer was prepared on the ITO coated glass substrates by IBSD at room temperature, and then, ZnO nanotip arrays were epitaxially grown on the as-prepared ZnO seed layer coated ITO/Glass substrates by hydrothermal method. The surface morphology study confirmed that the ZnO nanotip array films were epitaxially grown on ITO/Glass substrates, and it clearly showed the formation of well-aligned ZnO nanotip arrays on ITO/Glass substrate. The as-prepared samples were annealed at different temperatures (100, 150 and 270°C). After annealing, the surface morphology of ZnO nanotip arrays did not show any remarkable change. X-ray diffraction pattern of ZnO nanotip array films prepared on ITO/Glass showed a main peak at 2θ=34.3°, which corresponds to (002) plane. The photoluminescence spectra showed the strong intensity of UV emission and weak intensity of green emission. The J–V characteristic of Ag/NPB/PMMA/ZnO/ITO showed good rectification behavior.