Nickel Thin Films Research Articles

Localized to Propagating Surface Plasmon Resonance Transition in Ni-Au Magneto-Plasmonic Gratings

Magneto-plasmonic structures, which are the best candidates for different applications, have been the subject of intense research in recent years. In this paper, we proposed new magneto-plasmonic structures based on different uni-dimensional gratings to investigate the localized to propagative surface plasmon resonance transition. For this purpose, simulation of reflectance and also surface plasmon resonance coupling were used in three different fabricated samples compared with nickel thin film under different azimuthaly excitations. The fabricated samples show an enhanced magneto-optical rotation due to the transition of two types of plasmon in the sample with intermediate dimensions. The prospects of magneto-plasmonic response dependency on the azimuthaly excitation are discussed.

Electroless Nickel Deposition for Front Side Metallization of Silicon Solar Cells.

In this work, nickel thin films were deposited on texture silicon by electroless plated deposition. The electroless-deposited Ni layers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), X-ray diffraction analysis (XRD), and sheet resistance measurement. The results indicate that the dominant phase was Ni2Si and NiSi in samples annealed at 300–800 °C. Sheet resistance values were found to correlate well with the surface morphology obtained by SEM and the results of XRD diffraction. The Cu/Ni contact system was used to fabricate solar cells by using two different activating baths. The open circuit voltage (Voc) of the Cu/Ni samples, before and after annealing, was measured under air mass (AM) 1.5 conditions to determine solar cell properties. The results show that open circuit voltage of a solar cell can be enhanced when the activation solution incorporated hydrofluoric acid (HF). This is mainly attributed to the native silicon oxide layer that can be decreased and/or removed by HF with the corresponding reduction of series resistance.

Growth and Characterization of Metastable Hexagonal Nickel Thin Films via Plasma-Enhanced Atomic Layer Deposition

There is a great interest in various branches of the advanced materials industry for the development of novel methods (and improvements to existing ones) for the deposition of conformal ultrathin metallic films. In most of these applications, like enhanced solar absorbers and microelectronics, achieving the capacity to deposit a conformal thin film on a three-dimensional structure is an important condition. Plasma-enhanced atomic layer deposition (ALD) is known for its potential for growth of conformal thin films with a precise control over the thickness and its capability for deposition at relatively low temperatures (below 500 °C). This study evaluates the potential of plasma-enhanced ALD for growth of conformal nickel thin films, using bis(ethylcyclopentadienyl)nickel and nitrogen/hydrogen plasma as precursors. A comprehensive analysis of the structure, composition, and physical properties of the films was performed. The results indicate that conformal nickel films with low levels of impurity were successfully deposited on sapphire. The films had a roughness of Ra = 1.5 nm and were seen to be under strain. The deposited nickel had a hexagonal crystal structure, with a random in-plane orientation of the grains, while the grains had their c-axes oriented along the normal to the interface. These results pave the way for conformal low-temperature deposition of high-quality nickel thin films on three-dimensional structures.

Properties of NiO nanostructured growth using thermal dry oxidation of nickel metal thin film for hydrogen gas sensing at room temperature

A highly qualitative NiO nanostructure was synthesized using thermal dry oxidation of metallic Ni thin films on ITO/glass using the RF sputtering technique. The deposited nickel thin films were oxidized in air ambient at 550 °C inside a furnace. The structural and surface morphologies, and the electrical and gas sensing properties of the NiO nanostructure were examined. An x-ray diffraction analysis demonstrated that the NiO nanostructure has a cubic structure with orientation of the most intense peak at (2 0 0), and shows good crystalline quality. Finite-element scanning electron microscopy and energy dispersive x-ray spectroscopy results revealed O and Ni present in the treated samples, indicating a pure NiO nanostructure composition obtained with high porosity. The electrical properties of the oxidize Ni thin films showed a p-type NiO thin film semiconductor. A hydrogen gas sensing measurement was made at different operating temperatures and different gas concentrations with a detection limit of 30 ppm concentration. The sensor device shows great sensing properties with an excellent sensitivity (310%) at room temperature, which decreases with an increase in the operating temperature. Superfast response and recovery times of 6 and 0.5 s, respectively, were observed with the device at 150 °C operating temperature.

Accelerated quasicontinuum: a practical perspective on hyper-QC with application to nanoindentation

Hyper-QC is a multiscale method based on the quasicontinuum (QC) method in which time is accelerated using hyperdynamics through the addition of a suitable bias potential. This paper describes the practical details of implementing and carrying out hyper-QC simulations and introduces a novel mechanism-based bias potential for deformation processes in face-centred cubic (fcc) systems. The factors limiting the maximum achievable acceleration are discussed. The method is demonstrated for nanoindentation into a thin film of single crystal fcc nickel at near experimental loading rates. Speed up factors as high as 10,000 are achieved. The simulations reveal a thermally activated dislocation nucleation mechanism with a logarithmic dependence on temperature and indenter velocity in agreement with a theoretical model.

Formation of Low-Resistivity Nickel Germanide Using Atomic Layer Deposited Nickel Thin Film

Nickel germanide (NiGe) was formed from atomic layer deposition (ALD) Ni on Ge and a subequent annealing process; the Ni film with low resistivity ( $34~\mu \Omega \cdot \text {cm}$ ) at 15 nm was obtained by N2 + H2 plasma treatment after Ni precursor injection. The formed NiGe film showed low specific contact resistivity ( $\rho _{c})$ values of 9.01 $\mu \Omega \cdot \text {cm}^{2}$ for an NiGe/n+Ge contact and 3.61 $\mu \Omega \cdot \text {cm}^{2}$ for an NiGe/p+Ge contact. These values were comparable to those obtained using sputtered Ni. In addition, the ALD process-based NiGe showed excellent thermal/electrical stability up to 600 °C.

Optimization of an MEMS Magnetic Thin Film Vibrating Magnetometer

This paper presents models developed through analytical or numerical computation and finite-element analysis to improve the resolution of a new kind of vibrating magnetometers. This peculiar magnetometer uses the piezoelectric transduction to actuate a quartz resonator at its resonance frequency taking advantage of the high $Q$ factor of a quartz resonator to achieve high resolution. The magnetic sensitive element is a thin ferromagnetic film of nickel–cobalt, which is sputtered on the moving beams of the resonator. This magnetic thin film applies a periodic torque on the resonator, shifting its resonance frequency. This torque depends on the magnetic field applied; therefore, the value of the magnetic field can be deduced from the frequency shift measurement. The aim of this paper is to develop and improve sensitivity models, which will be useful tools in the future work to establish the optimal geometry for a resonator and the best position of the magnetic thin film on it in order to improve the sensitivity and resolution of the global sensor.

Charge transfer resistance of copper and nickel thin film electrodes in nano dimensions

Cu and Ni films with thickness ranging from 10 to 200nm were sputter deposited and their electrochemical impedance was investigated by impedance spectrum to develop the relationship between thickness of thin film electrodes and interface electrochemistry. Both charge transfer resistance and double layer capacitance of the film electrodes decreased with increase in thickness of the thin film electrodes. The current work provided further understanding on interface electrochemistry of thin film electrodes and served as guidance for the design of high performance miniature electrochemical devices.

Sputter deposition of Titanium and Nickel thin films in radio frequency magnetron discharge characterized by optical emission spectroscopy and by Rutherford backscattering spectrometry

By using a homemade dual magnetron sputtering system, two combined investigations by Optical emission spectroscopy and by Rutherford backscattering spectrometry were performed on a Radio-Frequency discharge for Titanium and Nickel deposited in pure Argon gas. Line intensities of various species present in the plasma were compared to the Argon emission line I of 696.5nm for different gas pressure and power density values. The electron temperature was also determined from the collisional radiative model and then correlated to the gas pressure and the power density. It was found that the sputtering pressure alters the spectrum intensity of Nickel, but has no obvious effect on that of Titanium during sputtering. The variation of average deposition rate as a function of gas pressure was experimentally determined via the Rutherford backscattering technique and then correlated to the variation of electron temperature of (Titanium-Argon) and (Nickel-Argon) discharges versus gas pressure.

Non-enzymatic hydrogen peroxide detection at NiO nanoporous thin film- electrodes prepared by physical vapor deposition at oblique angles

In this work we report a non-enzymatic sensor for hydrogen peroxide (H2O2) detection based on nanostructured nickel thin films prepared by physical vapor deposition at oblique angles. Porous thin films deposited on ITO substrates were characterized by X-ray diffraction analysis, scanning electron microcopy (SEMs), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques such as Cyclic Voltammetry (CV) and Constant Potential Amperometry (CPA). The microstructure of the thin films consisted of inclined and separated Ni nanocolumns forming a porous thin layer of about 500nm thickness. Prior to their use, the films surface was electrochemically modified and the chemical state studied by CV and XPS analysis. These techniques also showed that Ni2+/Ni3+ species were involved in the electrochemical oxidation and detection of H2O2 in alkaline medium. Main analytical parameters such as sensitivity (807mAM−1cm−2), limit of detection (3.22μM) and linear range (0.011–2.4mM) were obtained under optimal operation conditions. Sensors depicted an outstanding selectivity and a high stability and they were successfully used to determine H2O2 concentration in commercial antiseptic solutions.

Synthesis of Single‐Layer Graphene on Nickel Using a Droplet CVD Process

A liquid metal “droplet” chemical vapor deposition (CVD) process is developed for the synthesis of single‐layer graphene flakes utilizing molten nickel droplets (nominal diameter from 0.5 to 1 µm) as the catalysts. Ultrathin nickel films melt and form nickel droplets at around 1000 °C, providing liquid‐phase, single‐grain catalytic sites for the nucleation of graphene flakes via carbon precipitation process. Experimentally, both single and double‐layer graphene flakes with low defects have been synthesized by using nickel thin films of either less or more than 100 nm (up to 130 nm) in thickness, respectively. Furthermore, the synthesized graphene flakes are hybridized by the nickel orbitals as suggested by a density function analysis and experimentally observed blue shifts in Raman spectra tests. When the original nickel thin film is 75 nm in thickness, the resulting nickel droplets are physically and electrically isolated, while the graphene flakes are found to be electrically connected probably due to the outgrowth of graphene from the separated nickel droplets. These electrically connected graphene sheets could be readily available for device applications without the need of transfer processes. This work demonstrates the direct generation of photocurrents (up to 0.53 µA mm−2 W−1) due to the photothermal effect based on as‐fabricated graphene sheets under a visible light source.

Structural, chemical and magnetic properties of nickel vertical posts obtained by glancing angle deposition technique

In this work, Glancing Angle Deposition technique was used for obtaining nanostructured nickel thin film with vertical posts on glass substrate which was positioned 75 degrees with respect to the substrate normal and rotated with a suitable constant speed. The obtained nickel thin film was characterized by Scanning Electron Microscopy, Atomic Force Microscopy and X-ray Photoelectron Spectroscopy. It was found that the deposited thin film consists of 94.0 at.% of nickel. Magnetic properties of the deposited thin film were determined by Magneto-Optical Kerr Effect Microscopy. According to the obtained coercivity values, it can be concluded that the nickel thin film shows uniaxial magnetic anisotropy.

Relative SHG measurements of metal thin films: Gold, silver, aluminum, cobalt, chromium, germanium, nickel, antimony, titanium, titanium nitride, tungsten, zinc, silicon and indium tin oxide

We have experimentally measured the surface second-harmonic generation (SHG) of sputtered gold, silver, aluminum, zinc, tungsten, copper, titanium, cobalt, nickel, chromium, germanium, antimony, titanium nitride, silicon and indium tin oxide thin films. The second-harmonic response was measured in reflection using a 150fs p-polarized laser pulse at 1561nm. We present a clear comparison of the SHG intensity of these films relative to each other. Our measured relative intensities compare favorably with the relative intensities of metals with published data. We also report for the first time to our knowledge the surface SHG intensity of tungsten and antimony relative to that of well known metallic thin films such as gold and silver.

The oxidation kinetics of thin nickel films between 250 and 500 °C.

The oxidation kinetics of thin polycrystalline Ni films is of fundamental interest as well as being relevant for potential applications. It was investigated between 250 and 500 °C for 10-150 nm thick films. Even for the thinnest films, oxidation was found to be diffusion controlled. The high density of grain boundaries in the formed NiO layer leads to a tracer diffusion coefficient that is higher than reported in the literature, indicating accelerated Ni diffusion along the grain boundaries. Cr segregation to the bottom interface in doped-NiO films hindered the acceleration of the oxidation of thin films.

合成マイカ上の原子レベルで平坦なNi膜基板の作成方法

Synthetic mica was employed as a substrate for thin film growth and atomically flat Nickel thin film was heteroepitaxially formed. In addition to the small rms surface roughness achieved (< 1 nm), the surface morphology appears to be comparable to that of commercially available gold mica. Film growth was not complicated and consisted of nickel deposition and substrate annealing. The authors expect that as long as synthetic mica and standard film growth techniques are available, our results can be reproduced easily.

Enhanced Oxygen Evolution during Water Electrolysis at De-Alloyed Nickel Thin Film Electrodes

Hydrogen as an energy carrier has tremendous potential to overcome global warming issues. In this respect, production of hydrogen by water electrolysis has already been intensively studied, but its efficiency, especially in terms of the oxygen evolution reaction (OER), still needs to be improved. The objective of this work is to study the possibility of reducing the OER overpotential by de-alloying Ni thin film electrodes in order to favor bubble detachment. Ni(Al) alloys were first deposited by magnetron co-sputtering, and then chemically leached in a concentrated hydroxide solution with the aim of dissolving out the aluminum. We report X-ray diffraction analysis, scanning electron microscopy, inductively coupled plasma optical emission spectroscopy and roughness measurements to characterize our (de-)alloyed electrodes. Electrochemical testing, both cyclic voltammetry and chrono-potentiometry, has then been realized in a homemade electrochemical flow cell. Results show that different electrode compositions and intermetallic phases can be obtained by varying the deposition parameters, allowing to generate different Al/Ni atomic ratio's in the as-deposited films. Moreover, our de-alloyed electrodes present significantly lower overpotentials for the OER than untreated pure Ni electrodes. In the optimal case, a drop of as much as 140 mV was obtained at 10 mA/cm².

Non-enzymatic glucose sensing on copper-nickel thin film alloy

A simple and cost efficient glucose sensor was constructed using 3D printing having as active material a copper-15 at.% nickel thin film thermally co-evaporated on copper plated circuit boards. The glucose detection in alkaline solution was studied in detail by cyclic voltammetric and chronoamperometric measurements. The sensor suitability for being used in both quantitative and qualitative glucose detection was demonstrated and calibration of its response to various amounts of glucose revealed two linear regimes with different sensitivities. Glucose levels between 0 and 10mM are most efficiently quantified as indicated by an amperometric signal increase of 240μAcm−2 for each 1mM increase of glucose concentration. The potentiostatic stability of the sensor was evaluated and its complete insensitivity after 7h was solely attributed to the irreversible transformation of glucose into gluconolactone. A sensor life time of 20 cycles was demonstrated during potentiodynamic cycling when the sensor response remains constant at its maximum level. The magnitude of possible glucose quantification errors were evaluated as interferences induced by additions of ascorbic and uric acids. A worst case scenario of 96 % accuracy of glucose levels quantification was demonstrated using 25 times higher concentrations of interfering substances as compared to the glucose level.

Vertically Formed Graphene Stripe for 3D Field-Effect Transistor Applications.

A 100-nm wide, vertically formed graphene stripe (GS) is demonstrated for three-dimensional (3D) electronic applications. The GS forms along the sidewall of a thin nickel film. It is possible to further scale down the GS width by engineering the deposited thickness of the atomic layer deposition (ALD) Ni film. Unlike a conventional GS or graphene nanoribbon (GNR), the vertically formed GS is made without a graphene transfer and etching process. The process integration of the proposed GS FETs resembles that of currently commercialized vertical NAND flash memory with a design rule of less than 20 nm, implying practical usage of this formed GS for 3D advanced FET applications.

The influence of deposition temperature on the structure, microstructure, morphology and magnetic properties of sputter deposited nickel thin films

This paper reports the evolution of microstructure and texture and their correlation with the magnetic properties of Nickel thin films fabricated by direct current (DC) magnetron sputtering on a Silicon (100) substrate kept at different temperatures. The structural and microstructural investigations employing an X-ray diffraction line profile analysis (XRD-LPA) revealed an increase in the grain size and a significant reduction in the dislocation density by increasing the substrate temperature. The crystallographic texture of the films was characterized by a preferred (111) orientation in the films, irrespective of the deposition temperature. However, the evolution of a recrystallization cube texture (100) 〈001〉 was also observed with an increase in the deposition temperature in the films. The microstructure of the films deposited at room temperature showed a columnar growth morphology along the cross-section. The development of an equi-axed microstructure at higher temperatures was attributed to a higher mobility, enhanced surface and the bulk diffusion of ad-atoms arriving on the surface. A transition from soft to a hard magnetic character has been observed with an increase in deposition temperature. The magnetic force microscopy (MFM) revealed the presence of strip domains in the films deposited at room temperature. The presence of closure domains with disordered strip domains in the films deposited at 600°C was correlated with an increase in the disorder function, hard magnetic character and magnetic anisotropy in the film.

Effect of thickness on optical properties of nickel vertical posts deposited by GLAD technique

Nickel (Ni) thin films of different thicknesses (25 nm to 150 nm) were deposited on glass substrates using Glancing Angle Deposition technique. Characterization of obtained Ni films was performed by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, spectroscopic ellipsometry and by four-point probe method. Variations in optical parameters with thickness correlated with structural, chemical and electrical properties of nanostructured nickel thin films were studied. The results showed that deposit is porous and consists of nano-scaled columns, which grow perpendicular to the substrate. It was found that the size of the columns and the surface roughness change with film thickness. Spectroscopic ellipsometry revealed that the refractive index and extinction coefficient varied with thickness, which can be correlated with changes in microstructure of Ni films. Additionally, the relationship between the film microstructure and its resistivity was also analyzed. It was found that the variations in Ni films resistivity could be attributed to the changes in the width of the columns. The increasing of layer thickness leads to overall decrease of optical resistivity of nickel thin films.