Trilayer Thin Films Research Articles

Perpendicular Magnetic Anisotropy in CoSiB/Pd/CoSiB Trilayer Thin Films with Varying Pd-Layer Thicknesses.

We investigate the magnetic properties of CoSiB (1 5-Å-thickness)/Pd (Pd thickness = 8, 11, 14, 17, 20, 24, 27, 29 and 33 Å)/CoSiB (15-Å-thickness) trilayer thin films. The CoSiB-layer thickness was fixed to 15 Å, while the Pd-layer thickness was varied from 8-33 Å. In this paper, we present a new type of thin film containing amorphous Co75Si15B10 and Pd. We investigate the magnetic properties of a fabricated CoSiB/Pd/CoSiB trilayer thin film with perpendicular magnetic anisotropy, and determine the correlation between the magnetic properties and the nonmagnetic Pd-layer thickness. With increasing Pd-layer thickness, both the coercivity and the saturation magnetization decreased. Furthermore, the maximum values of the magnetic anisotropy were calculated as 0.3 x 10(6) erg/cc. In order to examine the difference between the in-plane magnetic anisotropy and perpendicular magnetic anisotropy, magnetic force microscopy images of the CoSiB (15-Å-thickness)/Pd (Pd thickness = 8 and 14 Å)/CoSiB (15-Å-thickness) trilayer thin films were obtained.

Study of interface correlation in W/C multilayer structure by specular and non-specular grazing incidence X-ray reflectivity measurements

W/C/W tri-layer thin film samples have been deposited on c-Si substrates in a home-built Ion Beam Sputtering system at 1.5 × 10−3 Torr Ar working pressure and 10 mA grid current. The tri-layer samples have been deposited at different Ar+ ion energies between 0.6 and 1.2 keV for W layer deposition and the samples have been characterized by specular and non-specular grazing incidence X-ray reflectivity (GIXR) measurements. By analyzing the GIXR spectra, various interface parameters have been obtained for both W-on-C and C-on-W interfaces and optimum Ar+ ion energy for obtaining interfaces with low imperfections has been found. Subsequently, multilayer W/C samples with 5-layer, 7-layer, 9-layer, and 13-layer have been deposited at this optimum Ar+ ion energy. By fitting the specular and diffused GIXR data of the multilayer samples with the parameters of each interface as fitting variables, different interface parameters, viz., interface width, in-plane correlation length, interface roughness, and interface diffusion have been estimated for each interface and their variation across the depth of the multilayers have been obtained. The information would be useful in realizing W/C multilayers for soft X-ray mirror application in the <100 Å wavelength regime. The applicability of the “restart of the growth at the interface” model in the case of these ion beam sputter deposited W/C multilayers has also been investigated in the course of this study.

Giant magnetoelectric coupling interaction in BaTiO3/BiFeO3/BaTiO3 trilayer multiferroic heterostructures

Multiferroic trilayer thin films of BaTiO3/BiFeO3/BaTiO3 were prepared by RF-magnetron sputtering technique at different thicknesses of BiFeO3 layer. A pure phase polycrystalline growth of thin films was confirmed from X-ray diffraction results. The film showed maximum remnant electric polarization (2Pr) of 13.5 μC/cm2 and saturation magnetization (Ms) of 61 emu/cc at room temperature. Thermally activated charge transport dominated via oxygen vacancies as calculated by their activation energy, which was consistent with current–voltage characteristics. Magnetic field induced large change in resistance and capacitance of grain, and grain boundary was modeled by combined impedance and modulus spectroscopy in the presence of varied magnetic fields. Presence of large intrinsic magnetoelectric coupling was established by a maximum 20% increase in grain capacitance (Cg) with applied magnetic field (2 kG) on trilayer having 20 nm BiFeO3 layer. Substantially higher magnetoelectric coupling in thinner films has been observed due to bonding between Fe and Ti atoms at interface via oxygen atoms. Room temperature magnetoelectric coupling was confirmed by dynamic magnetoelectric coupling, and maximum longitudinal magnetoelectric coupling of 515 mV/cm-Oe was observed at 20 nm thickness of BiFeO3. The observed magnetoelectric properties are potentially useful for novel room temperature magnetoelectric and spintronic device applications for obtaining higher voltage at lower applied magnetic field.

Solute redistribution and phase stability at FeCr/TiO2−x interfaces under ion irradiation

Cr diffusion in trilayer thin films of 100nm Fe–18Cr/125nm TiO2−x/100nm Fe–18Cr deposited on MgO substrates at 500°C was studied by either annealing at 500°C or Ni3+ ion irradiation at 500°C. Microchemistry and microstructure evolution at the metal/oxide interfaces were investigated using (high-resolution) transmission electron microscopy, energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy. Diffusion of Cr into the O-deficient TiO2 layer, with negligible segregation to the FeCr/TiO2−x interface itself, was observed under both annealing and irradiation. Cr diffusion into TiO2−x was enhanced in ion-irradiated samples as compared to annealed. Irradiation-induced voids and amorphization of TiO2−x was also observed. The experimental results are rationalized using first-principles calculations that suggest an energetic preference for substituting Ti with Cr in sub-stoichiometric TiO2. The implications of these results on the irradiation stability of oxide-dispersed ferritic alloys are discussed.

AZO/Au/AZO tri-layer thin films for the very low resistivity transparent electrode applications

Abstract Aluminum-doped ZnO (AZO)/gold/AZO tri-layer structures with very low resistivity and high transmittance are prepared by simultaneous RF magnetron sputtering (for AZO) and ion sputtering (for Au). The properties of the tri-layer films are investigated at different Au layer thicknesses (5–20 nm). The effects of Au layer thickness and the role of Au on the transmission properties of the tri-layer films were investigated. The very low resistivity of 1.01 × 10−5 Ω cm, mobility of 27.665 cm2 V−1 s−1, and carrier concentration of 4.563 × 1022 cm−3 were obtained at an Au layer thickness of 20 nm. The peak transmittance of 86.18% at 650-nm wavelength was obtained at an Au layer thickness of 8 nm. These results show the films to be a good candidate for high-quality electrode scheme in various display applications.

Enhancement of the magnetic interfacial exchange energy at a specific interface in NiFe/CoO/Co trilayer thin films via ion-beam modification

A series of ferromagnetic Ni80Fe20(55 nm)/antiferromagnetic CoO (25 to 200 nm)/ferromagnetic Co (55 nm)/SiO2(substrate) trilayer thin films were fabricated by ion-beam assisted deposition in order to understand the role of ion beam modification on the interfacial and interlayer coupling. The microstructural study using transmission electron microscopy, X-ray reflectometry, and polarised neutron reflectometry showed that ion-beam modification during the deposition process led to an oxygen-rich Co/CoO nanocomposite interface region at the bottom layer. This interface caused a high exchange bias field for the ferromagnetic cobalt. However, the exchange bias for top permalloy ferromagnet remained low, in line with expectations from the literature for the typical interfacial energy. This suggest that the ion-beam enhancement of the magnetic exchange bias is localized to the Co/CoO interface where local microstructural effects provide the dominant mechanism.

High gas barrier imparted by similarly charged multilayers in nanobrick wall thin films

Super oxygen barrier trilayer thin films have been deposited using two successive anionic layers of clay and polymer following every cationic polymer layer.

Optical, ferroelectric and magnetic properties of multiferroelectric BiFeO3–(K0.5Na0.5)0.4(Sr0.6Ba0.4)0.8Nb2O6 thin films

Multiferroic BiFeO3–(K0.5Na0.5)0.4(Sr0.6Ba0.4)0.8Nb2O6 (BFO–KNSBN) trilayer thin films, were epitaxially grown on MgO(0 0 1) and SrTiO3(0 0 1) by using pulsed laser deposition (PLD). Their ferroelectric, magnetic, dielectric and optical properties were investigated. It was found that both ferroelectric polarization and dielectric constant of the films were enhanced by introducing KNSBN as a barrier layer. Meanwhile, ferromagnetism of BFO was maintained. More interestingly, a double hysteresis magnetic loop was observed in the KNSBN–BFO–KNSBN trilayer films, where exchange bias and secondary phase in the BFO layer played crucial roles. Interactions between adjacent layers were revealed by temperature-dependent Raman spectroscopic measurements.

Phosphorous-filled nanobrick wall multilayer thin film eliminates polyurethane melt dripping and reduces heat release associated with fire

Abstract Unique trilayer (TL) thin films of sodium montmorillonite (MMT), poly(allylamine hydrochloride) (PAH) and poly(sodium phosphate) (PSP) are prepared via layer-by-layer (LbL) assembly. This three-component nanocoating completely shuts down melt dripping and reduces heat release of open-celled flexible polyurethane (PU) foam when exposed to direct flame due to a synergistic interaction between PSP and the thermally shielding clay platelets in the condensed phase. Post burn scanning electron microscopy reveals the nanocoating's swollen morphology is able to maintain foam shape, cellular structure, and porosity. Cone calorimetry reveals that 4 TL coated foams (

Characteristics of transparent conductive Al-doped ZnO and Ag–Ti tri-layer thin films prepared by multi-target magnetron sputtering

Al-doped ZnO (AZO) and Ag–Ti films were successfully deposited on glass substrates by multi-target magnetron sputtering to form the high transparent AZO/Ag–Ti/AZO multilayer. The optical, electrical properties and lifetime performance were investigated at various AZO and Ag–Ti thicknesses. As the AZO thickness was fixed at 10nm and Ag–Ti thickness was varied between 6 and 22nm, it can be found that AZO10nm/Ag–Ti10nm/AZO10nm possessed good conductivity and highest transmittance in visible region. Then an AZO thickness adjustment of 10–90nm was performed. With increasing AZO thickness from 10 to 70nm, the transmittances of AZO10–70nm/Ag–Ti10nm/AZO10–70nm films were all above 80% in the visible region and optimal transparency can be reached at AZO thickness of 70nm. Although the conductivity in AZO/Ag–Ti/AZO films was decreased with increasing Ag–Ti thickness, the resistivity of 4.95×10−4Ω-cm in AZO70nm/Ag–Ti10nm/AZO70nm was still acceptable. From the lifetime tests under normal circumstance, these multilayers almost showed the same transmittance and resistivity from 0 to 90days. Furthermore, the AZO70nm/Ag–Ti10nm/AZO70nm exhibits the highest figure of merit of 8.93×10−3Ω−1, indicating that the multilayer has high potential in optoelectronic applications.

High Temperature Magnetic Properties of Indirect Exchange Spring FePt/M(Cu,C)/Fe Trilayer Thin Films

We report the investigation of temperature dependent magnetic properties of FePt and FePt(30)/M(Cu,C)/Fe(5) trilayer thin films prepared by using magnetron sputtering technique at ambient temperature and postannealed at different temperatures. L10 ordering, hard magnetic properties, and thermal stability of FePt films are improved with increasing postannealing temperature. In FePt/M/Fe trilayer, the formation of interlayer exchange coupling between magnetic layers depends on interlayer materials and interface morphology. In FePt/C/Fe trilayer, when the C interlayer thickness was about 0.5 nm, a strong interlayer exchange coupling between hard and soft layers was achieved, and saturation magnetization was enhanced considerably after using interlayer exchange coupling with Fe. In addition, incoherent magnetization reversal process observed in FePt/Fe films changes into coherent switching process in FePt/C/Fe films giving rise to a single hysteresis loop. High temperature magnetic studies up to 573 K reveal that the effective reduction in the coercivity decreases largely from 34 Oe/K for FePt/Fe film to 13 Oe/K for FePt/C(0.5)/Fe film demonstrating that the interlayer exchange coupling seems to be a promising approach to improve the stability of hard magnetic properties at high temperatures, which is suitable for high‐performance magnets and thermally assisted magnetic recording media.

Fabrication of thin film TiO2 nanotube arrays on Co–28Cr–6Mo alloy by anodization

Titanium oxide (TiO2) nanotube arrays were prepared by anodization of Ti/Au/Ti trilayer thin film DC sputtered onto forged and cast Co–28Cr–6Mo alloy substrate at 400°C. Two different types of deposited film structures (Ti/Au/Ti trilayer and Ti monolayer), and two deposition temperatures (room temperature and 400°C) were compared in this work. The concentrations of ammonium fluoride (NH4F) and H2O in glycerol electrolyte were varied to study their effect on the formation of TiO2 nanotube arrays on a forged and cast Co–28Cr–6Mo alloy. The results show that Ti/Au/Ti trilayer thin film and elevated temperature sputtered films are favorable for the formation of well-ordered nanotube arrays. The optimized electrolyte concentration for the growth of TiO2 nanotube arrays on forged and cast Co–28Cr–6Mo alloy was obtained. This work contains meaningful results for the application of a TiO2 nanotube coating to a CoCr alloy implant for potential next-generation orthopedic implant surface coatings with improved osseointegrative capabilities.

Integration of thin film giant magnetoimpedance sensor and surface acoustic wave transponder

Passive and remote sensing technology has many potential applications in implantable devices, automation, or structural monitoring. In this paper, a tri-layer thin film giant magnetoimpedance (GMI) sensor with the maximum sensitivity of 16%/Oe and GMI ratio of 44% was combined with a two-port surface acoustic wave (SAW) transponder on a common substrate using standard microfabrication technology resulting in a fully integrated sensor for passive and remote operation. The implementation of the two devices has been optimized by on-chip matching circuits. The measurement results clearly show a magnetic field response at the input port of the SAW transponder that reflects the impedance change of the GMI sensor.

Study of tri-layer antireflection coatings prepared by sol–gel method

Antireflective coatings (ARCs) on tri-layer thin film stacks were studied in this paper. Silica sols have been prepared by acid-catalyzed or base-catalyzed hydrolysis and condensation reactions of tetraethyl orthosilicate. Antireflective nanometric SiO2/TiO2 films are formed on both sides of the glass substrates by combining the sol–gel method and the dip-coating technique. Seen from the transmittance spectra of different films, a maximum light transmittance of 99.9% was obtained at the band of 300–800 nm. Scanning electron microscope (SEM) and atomic force microscopy (AFM) confirm the well-covered surface morphology. By the SEM observations we can see that the films are full of coverage on glass surface and containing no voids or cracks. The image root mean square roughness of the two types of ARCs provided by the AFM is 1.21 and 3.04 nm, respectively. Furthermore, a surface profiler was used to determine the thickness of each layer in the obtained multi-layer coating system.

Effect of Al Nanoparticles on the Microstructure, Electrical, and Optical Properties of AZO/Al/AZO Trilayer Thin Film

In this work, designed growth of aluminum (Al)/aluminum-doped zinc oxide (AZO), AZO/Al/AZO, and AZO/Al multilayer electrodes by radiofrequency (RF) magnetron sputtering on glass substrates was studied. The microstructures, optical properties, and electrical characteristics of the multilayer electrode thin films were analyzed, their structural denseness and thickness were observed by field-emission scanning electron microscopy (FE-SEM), and their crystal orientation was identified by x-ray diffraction (XRD). The resistivity and transmittance of the films were measured by four-point probe and UV–Vis–NIR spectrophotometer, respectively. The resistivity of the AZO/Al/AZO multilayer electrode thin film was 1.55 Ω cm. The average transmittance of the AZO/Al/AZO thin film over wavelengths from 400 nm to 800 nm was much better than that of other thin films, since Al nanoparticles distribute in the AZO thin film during the sputtering process, as observed by high-resolution transmission electron microscopy (HRTEM). In addition, the figure of merit of the AZO/Al/AZO trilayer film was much larger than those of the other structures.

Mössbauer study 57Fe in ultrathin trilayer films with sharp and rough interfaces

Trilayer thin films Py/57Fe/Gd and Gd/57Fe/Py (Py: Fe20Ni80 permalloy) have been prepared by electron-beam evaporation and investigated using conversion-electron Mössbauer spectroscopy (CEMS), scanning tunneling microscopy (STM), polar magneto-optical Kerr effect (PMOKE), and ferromagnetic resonance (FMR). It was shown that the films deposited in the same vacuum and temperature runs but with the reverse order of the layers gave a different quality of interfaces: sharp (Py/57Fe/Gd) and rough (Gd/57Fe/Py). Different distribution of atoms in sharp and rough interfaces results in different magnetic properties: the Mössbauer spectra, FMR, and PMOKE data show the appearance of perpendicular magnetic anisotropy (PMA) and enhancement of magnetization in the samples with the rough Gd/Py interface.

Crystallization Mechanism and Raman Characteristics of ZnO/In/ZnO Thin Film Using an Electrical Current Method

ZnO/In/ZnO tri-layer thin films were designed and fabricated by RF sputtering on copolymer substrate. Under an electrical current, the thermoelectric effect of direct current (DC) reduced the electrical resistance and improved the crystallization and Raman properties. Also, indium atoms had migrated into the ZnO matrix and a diffusion layer in the ZnO/In interface had grown. The electrical current induced temperature is ∼140°C and the copolymer substrate suffers no damage and so can be applied to the low temperature optoelectronic devices.

Radiation damage effects in layered thin film MgO/HfO 2 structures

In this report, we present a study of a thin film tri-layer structure, HfO 2/MgO/HfO 2, irradiated at room temperature with 10 MeV Au ions over a wide fluence range from 5 × 10 13 to 3.7 × 10 16 Au/cm 2. The tri-layer structure is a model representation for the microstructure in a composite dispersion nuclear fuel or waste form. Microstructural and chemical composition changes were examined by transmission and scanning transmission electron microscopy (TEM & STEM) combined with energy dispersive X-ray spectroscopy (EDXS), grazing incidence X-ray diffraction (GIXRD) and Rutherford backscattering spectroscopy (RBS) techniques. The microstructural evolution in the HfO 2/MgO/HfO 2 trilayer was similar to the radiation damage behavior of the individual HfO 2 and MgO constituents. For instance, we observed an absence of amorphization in both the MgO and HfO 2 layers and a phase transformation of HfO 2 from the monoclinic to the tetragonal HfO 2 polymorph. In addition, we observed the formation of void-type defects at one of the MgO/HfO 2 interfaces. Such voids are not characteristic to either bulk material (MgO or HfO 2) exposed to ion irradiation.

Preparation and characterization of vacuum thermal evaporated trilayer Cu/Se/Al thin films

Trilayer thin films of Cu/Se/Al have physically deposited using vacuum thermal evaporation technique at pressure of 10 −5 Torr onto a glass substrate. Before and after annealing at different temperatures, various properties of these trilayer thin films, including the structure, optical absorption, optical band gap, current–voltage measurements and morphology have been studied and discussed. These properties have been characterized by X-ray diffraction (XRD), UV–vis spectrophotometer, 2 point probe and optical microscope at room temperature. Crystalline nature, resistance and band gap of annealed Cu/Se/Al trilayer thin films have been found to be increased comparative to the as deposited samples. Surface topography of as deposited and annealed trilayer thin films has been confirmed by 2D and 3D images of optical micrographs.

High field-sensitivity planar Hall sensor based on NiFe/Cu/IrMn trilayer structure

A trilayer structure, which has weak exchange coupling and high active current, has been optimized emphasizing for high field-sensitivity planar Hall effect (PHE) sensor. To illustrate the high field sensitivity of the PHE sensor, three different structures are fabricated: a bilayer thin film Ta(3)/NiFe(10)/IrMn(10)/Ta(3) (nm), a spin-valve thin film Ta(3)/NiFe(10)/Cu(1.2)/NiFe(2)/IrMn(10)/Ta(3) (nm), and a trilayer thin film Ta(3)/NiFe(10)/Cu(0.12)/IrMn(10)/Ta(3) (nm). The characterized results reveal that the field sensitivity of PHE sensor based on trilayer thin film is about one order larger than that of bilayer and is about twice larger than that of spin-valve thin film. Moreover, in trilayer structure, the thinner spacer layer gives the better performance. When the nominal thickness of spacer Cu layer is the smallest, the PHE sensor exhibits the best performance, i.e., in this experiment, it is about 0.12 nm.