Sandwich Films Research Articles

Absorption of Optical Microcavity in the Infrared Spectral Region

This paper describes an air Fabry-Perot (FP) cavity which is used in the infrared (IR) detector. When the distance of the FP cavity is wavelength-sized, it can store photons for almost a millisecond while they bounce up and down between the mirrors. Compared with another filled material, the air cavity not only gets high IR absorption when the cavity thickness is quarter wavelength, but also has much smaller thermal capacity and thermal time, which can improve the responsivity and detectivity of the IR detectors. An air FP cavity has been fabricated, with a thick metal mirror at bottom and a special sandwich film in the top served as absorption layer and semitransparent reflector. The materials and thickness are tested to optimize the absorption. According to the results, the best structure has been obtained, and the test results show that the IR absorption of this structure can reach to 85%.

Perovskite‐Based Hybrid Solar Cells Exceeding 10% Efficiency with High Reproducibility Using a Thin Film Sandwich Approach

Organometal halide perovskites have tremendous potential as light absorbers for photovoltaic applications. In this work we demonstrate hybrid solar cells based on the mixed perovskite CH3 NH3 PbI2 Cl in a thin film sandwich structure, with unprecedented reproducibility and generating efficiencies up to 10.8%. The successfulness of our approach is corroborated by the experimental electronic structure determination of this perovskite.

Single-component poly(ε-caprolactone) composites

Non-covalently bonded crystalline inclusion compounds (ICs) have been formed by threading host cyclic starches, α-cyclodextrins (α-CDs), onto guest poly(ε-caprolactone) (PCL) chains and by co-crystallization of guest PCL and host urea (U). PCLs were coalesced from both ICs by appropriate removal of the α-CD and U hosts. When added at low concentrations, PCL coalesced from its α-CD–IC served as an effective self-nucleating agent for the bulk crystallization of as-received PCL from the melt. Film sandwiches consisting of two layers of as-received (asr) (control), and one layer each of asr and self-nucleated (nuc) (composite) PCLs were produced by melt pressing. A composite sandwich consisting of a film of neat PCL coalesced from its U–IC (c-PCL) and a film of asr-PCL was also melt pressed. DSC showed that both composite films maintain their characteristic structures and properties even after melt-pressing them together. Both single component film sandwiches exhibited strong interfaces and better mechanical properties than the asr-PCL/asr-PCL control composite sandwiches. These results are similar to those previously obtained on similarly prepared nylon-6 (N-6) sandwich composites made with asr- and nuc-N-6 films with the same levels of crystallinity. However, while the elongation at break was greatly reduced in the asr-N-6/nuc-N-6 composite, asr-/asr-, asr-/c-, and asr-/nuc-, PCL/PCL-composites all showed similarly large elongations at break. The above room temperature and well below room temperature glass-transition temperatures of N-6 and PCL are likely the cause of their widely different elongations at break.

Synthesis and optical behavior of PLED devices based on (PMMA)/(PAA)/Er(AP)6Cl3 complex and N,N′-didodecyl-3,4,9,10-perylene tetracarboxylic diimide composites

The realization of efficient polymeric light emitting diode (PLEDs) in a double-layered configuration was investigated. The devices are composed by transparent conductive oxide (ITO)/MoO3/organic layers/aluminum/selenium, conformed by thin film sandwich structures obtained by vacuum evaporation. Two organic layers were developed. First a n-type organic layer of composite based on polymethylmethacrylate (PMMA)/polyacrilic acid (PAA)/Er(AP)6Cl3 complex and second a n-type organic semiconductor, N,N′-didodecyl-3,4,9,10-perylene tetracarboxylic diimide (PTCDI-C12H25). The rare earth complex composites and the perilenic compound were synthesized and characterized using UV–Visible absorption, XPS, and NMR techniques, respectively. Driving voltage of devices was lowered by applying MoO3 thin film as buffer layer and high current intensity efficiency was obtained applying a perilenic film. The effect of MoO3 and PTCDI-C12H25 thin films, on the optical and the physical properties of the electroluminescent devices were discussed. I–V measurements have shown that the structures exhibit diode characteristics and the electroluminescent signal increases when PTCDI-C12H25 thin layer is introduced between the anode and the holes transporting layer. The morphology of the thin films with and without buffer layer indicates that introduction of this layer allows to obtain a homogeneous surface morphology. The results indicate that carrier injection ability and optimized charge balance is obtained to the lowest driving voltage and highest intensities efficiency among the referenced devices.

Anthracene dopping effects on thin films properties of octakis(alkylthio) substituted lutetium bisphthalocyanine

In this work, the investigation of structural features, spectral and electrical properties of spin-coated films of substituted lutetium bisphthalocyanine Lu ( Pc ( SR )8)2, where R = - C 6 H 13 was carried out. The current-voltage characteristics of ITO/ Lu ( Pc ( SR )8)2/ Al film sandwich structures were measured over the temperature range 120–380 K. AC electrical properties, mainly the dependence of conductance and capacitance on frequency and temperature are also discussed. Structural and electrical properties of anthracene-doped Lu ( Pc ( SR )8)2, films have also been investigated. Furthermore, optical properties of thin films of pure and anthracene-doped Lu ( Pc ( SR )8)2 films were also studied using spectroscopic ellipsometry, while atomic force microscopy (AFM) was used to study changes in films' morphology of doped films and compared with that of undoped films. Doping Lu ( Pc ( SR )8)2, films with anthracene is shown to lead to an increase in films' conductivity. These studies will provide full understanding of the physical properties of the Lu ( Pc ( SR )8)2, thin films, both doped and undoped, with the aim of exploitation in electronic device applications, such as fabrication of all organic solar cells.

Metal/dielectric/metal sandwich film for broadband reflection reduction

A film comprising randomly distributed metal/dielectric/metal sandwich nanopillars with a distribution of cross-sectional diameters, displayed extremely low reflectance over the blue-to-red regime, when coated on glass and illuminated normally. When it is illuminated by normally incident light, this sandwich film (SWF) has a low extinction coefficient, its phase thickness is close to a negative wavelength in the blue-to-red spectral regime, and it provides weakly dispersive forward and backward impedances, so that reflected waves from the two faces of the SWF interfere destructively. Broadband reflection-reduction, over a wide range of incidence angles and regardless of the polarization state of the incident light, was observed when the SWF was deposited on polished silicon.

Annealing induced compositional changes in SmCo5/Fe/SmCo5 exchange spring trilayers and its impact on magnetic properties

SmCo5/Fe/SmCo5 sandwich configurations have gained renewed interest when compared to the conventional SmCo5/Fe bilayers, as they exhibit enormous scope to impart high energy product values with strong magnetization reversal behavior. The compositional changes that occur in the intermediate soft layer upon annealing play a critical role in determining the phase chemistry, as well as magnetic performance of the trilayers and herein we address such a study. SmCo5/Fe/SmCo5 sandwich films with fixed layer thicknesses of SmCo5 (25nm) and Fe (8nm) were grown by sputtering on Cr buffered Si (100) substrates and subsequently, annealed at different temperatures: 673, 773 and 873K. The effect of post-deposition annealing on the structure, composition and magnetic properties of the trilayer architecture was investigated by X-ray diffraction (XRD), Rutherford back-scattering (RBS) and super-conducting quantum interference device (SQUID), respectively. The XRD studies showed significant decrease in the lattice parameter values with increasing annealing temperature, which suggests an increase in the diffused Co-content in the Fe-intermediate layer. The XRD results were further validated by RBS measurements, which confirmed that both composition and thickness of the Fe-intermediate layer were strongly affected by the annealing temperature. The SQUID measurements demonstrated the existence of in-plane anisotropy and strong exchange coupling between the hard and soft layers for all the annealed sandwich films. The trilayer stack annealed at 773K showed the best magnetic performance such as high coercivity (814kA/m), remanence (944kA/m) and energy product (243kJ/m3).

Structural and optical properties of fullerene-like amorphous carbon with embedded dual-metal nanoparticles

Dual-metal nanoparticles were simultaneously embedded into amorphous carbon (a-C) matrix at room temperature. As-deposited Au/a-C/Fe sandwich composite multilayer films were fabricated by alternating multitarget pulsed laser deposition. More sp2 carbon content, narrower Tauc optical gap and stronger photoluminescence intensity of the amorphous carbon films were observed after metal-embedding. Especially for Au/a-C/Fe sandwich films, the fullerene-like microstructure demonstrated that the dual-metal embedding modulated greatly the intrinsic structure and properties of the a-C films. These results were attributed primarily to the extended state around the metal deep level in the band gap and the narrowing of the π and π∗ band edge states. The metal deep level defects contributed chiefly to non-radiative recombination.

Catalytic synthesis of crystalline SiC nanowires from a Ni/a-C/Si sandwich configuration

High quality 3C-SiC nanowires are synthesized via thermal treatment of Ni/a-C/Si sandwich films. The nanowires obtained at 900 °C, under a low partial pressure of oxygen, consist of 20–50 mm diameter cores coated by an amorphous phase. The formation of 3C-SiC involves solid–liquid–solid mode and vapor–liquid–solid processes. The ability to synthesize SiC nanowires under the fabrication conditions, both relatively low temperature and a small amount of oxygen, represents an important advance towards their eventual integration for various technological applications.

Response to “Comment on ‘Silver/silicon dioxide/silver sandwich films in the blue-to-red spectral regime with negative-real refractive index’” [Appl. Phys. Lett. 101, 156101 (2012)

Response to “Comment on ‘Silver/silicon dioxide/silver sandwich films in the blue-to-red spectral regime with negative-real refractive index’” [Appl. Phys. Lett. 101, 156101 (2012)

Comment on “Silver/silicon dioxide/silver sandwich films in the blue-to-red spectral regime with negative-real refractive index” [Appl. Phys. Lett. 99, 181117 (2011)

First Page

基于双抗体夹心传感膜的信号增强方法用于致癌基因c-myc蛋白的检测

A kind of signal enhanced electrochemical biosensor based on double antibody sandwich film modified Au electrode was prepared by using layer-by-layer self-assembly technique. The Au electrode was firstly assembled with L-cysteine and glutaraldehyde, then fixed with c-Myc (9E10) monoclonal antibody (C-Ab1), resulting in forming a C-Ab1 modified electrode, which was able to recognise the c-myc oncogene protein. After combining with a second antibody of anti-mouse IgG (H+L) antibody (C-Ab2), the double antibody sandwich film (C-Ab1/c-myc/C-Ab2) modified electrode was obtained, in which the response signal was greatly enhanced, and the sensing property was better than that of the C-Ab1 modified electrode. The mechanism for signal enhancement with the double antibody sandwich method was explored through electrochemical impedance analysis and cyclic voltammetry behaviors. The impedance value of C-Ab1/c-myc/C-Ab2 modified biosensor was linearly proportional to the logarithmic concentrations of c-myc protein over the range of 0.043-430 nM, and the linear equation was fitted as <italic>Y</italic> = 10046.10 + 863.33<italic>X</italic> with a correlated coefficient of 0.9904. The detection limit of c-myc protein was evaluated to be 25.76 pM. The biosensor was simply prepared which possessed nice selectivity, reproducibility, stability and regenerability, and could be applied for determination of c-myc in rat serum with a recovery from 97.4% to 103.7%, indicating its practical application on detection of c-myc in tumor samples with potential value in biomedical field.

Ferroelectric and Optical Properties of BST/BZT/BST Sandwich Structure Thin Films Prepared by RF Sputtering

In this work, (Ba0.65Sr0.35)TiO3 (BST) and Ba(Zr0.20Ti0.80)O3 (BZT) ceramic targets were prepared using the traditional solid-state reaction technique, which were sintered at 1200 °C for 2 h. The thin films of BST, BZT and sandwich structure BST/BZT/BST were grown on Pt/Ti/SiO2/Si(100) and Si(100) substrates by rf-sputtering at 500 °C, respectively. And all samples crystallied at temperatures 650 °C for 30 min in oxygen atmosphere. The cross-sectional images of the thin films were characterized by scanning electron microscope (SEM). The dielectric constant and dissipation factor tan of the BZT, BST and BST/BZT/BST thin films are 680 and 0.030, 240 and 0.021, 85 and 0.018, respectively at 100 kHz. Compared with BST and BZT films, the BST/BZT/BST film has lower dielectric constant and lower dissipation. The remanent polarization (Pr) of the sandwich structure BST/BZT/BST thin film is up to 9.57 μC/cm2, the Pr value is larger than that BST (0.25μC/cm2) film and BZT (8.45μC/cm2) film. The optical properties (refractive index n and extinction coefficient k) of the BST/BZT/BST film on Si(100) substrate were measured by n &amp; k analyzer 2000.

Piezoelectric performance of fluor polymer sandwiches with different void structures

Film sandwiches, consisting of two outer layers of fluoroethylenepropylene and one middle layer of patterned porous polytetrafluoroethylene, were prepared by patterning and fusion bonding. Contact charging was conducted to render the films piezoelectric. The critical voltage to trigger air breakdown in the inner voids in the fabricated films was investigated. The piezoelectric d33 coefficients were measured employing the quasistatic method and dielectric resonance spectrum. The results show that the critical voltage for air breakdown in the inner voids is associated with the void microstructure of the films. For the films with patterning factors of 0%, 25% and 44%, the critical values are 300, 230 and 230 kV/cm, respectively. With an increase in the patterning factor, both the piezoelectric d33 coefficients determined from the dielectric resonance spectra and those determined from quasistatic measurements increase, which might be due to a decrease in Young’s modulus for the films. The nonlinearity of d33 becomes increasingly obvious as the patterning factor increases.

Preparation of synthetic antiferromagnetic coupled FeCoN/Ru/FeCoN films

The FeCoN/Ru/FeCoN sandwich films were deposited on glass substrate by magnetron sputtering system. The antiferromagnetic behavior of FeCoN sandwich films can be tuned by varying the thickness of FeCoN layer and Ru interlayer, the preparation conditions such as the sputtering power of FeCoN layer, and the oblique angle when deposited. It is found that effective anisotropy field (Hk) relates to the exchange coupling field (Hex) in synthetic antiferromagnetic sandwich films. The synthetic antiferromagnetic films with high saturation magnetization (Ms), large exchange coupling field (Hex) and Hk were obtained by using the optimum thickness, low sputtering power of FeCoN layers and big oblique angle when deposited, which is very suitable for the soft magnetic underlayer's (SUL) applications.

Low-Resistivity Ru-Ta-C Barriers for Cu Interconnects

Ru-Ta-C films deposited on silicon substrates were evaluated as barriers for copper metalization. The films were prepared by magnetron cosputtering using a Ru target and a Ta-C target. Compositions and structure of resultant films were optimally tuned by the respective deposition power of each target. The fabricated Ru-Ta-C films were characterized via four-point probe measurement, x-ray diffractometry, field-emission electron probe microanalysis, and transmission electron microscopy. Failure temperature was evaluated by the sudden rise in electrical resistivity after annealing the Cu/Ru-Ta-C/Si sandwich films, and a reference bilayer Cu/(5 nm Ru)/(5 nm Ta-C)/Si scheme. The optimal compositions were 10 nm Ru77Ta15C7 and (5 nm Ru)/(5 nm Ta-C), both of which showed failure temperature of 650°C for 30 min and electrical resistivity less than 150 μΩ cm. Because of their high thermal stability and low electrical resistivity, both Ru-Ta-C and Ru/Ta-C films are promising barriers for Cu metalization.

Electrospun Nanofibre Cores Containing Graphene Oxide for Sandwich Films: Manufacturing and Analysis

The motivation for the need of small-scale devices has made thin films technologically important in the recent years. They have found applications in broad fields, such as microelectronic integrated circuits, magnetic information storage systems, optical coatings and wear resistant coatings. However, the mechanical performance of these materials tends to depend on fabrication and post-processing parameters. With the intent of improving the mechanical properties of the films, a relatively novel concept of sandwich composite films has been tried in this research. Poly-methyl methacrylate (PMMA) and Graphene Oxide (GO) have been used to manufacture the sandwich films, where PMMA films have served as the facings and electrospun PMMA/GO nanofibre mat forms the sandwich core. Dimethylformamide (DMF) and Tetrahydrofuran (THF) solvents are used in suitable proportions to dissolve PMMA, and then GO is added to this solution to obtain a uniform suspension of PMMA/GO for electrospinning. The mechanical and functional properties depend on the fibre quality and their distributions in the mat, which in turn depends on the concentration of the solution. Therefore, design of experiments based on mixture analysis was used to identify the solution concentration for obtaining uniform fibre diameters and their distribution throughout the electrospun core. The analysis suggested 23% PMMA and 2% GO concentrations in the solution would give uniform fibre diameters and dispersion throughout the mat.

Silver/silicon dioxide/silver sandwich films in the blue-to-red spectral regime with negative-real refractive index

Sandwich films comprising arrays of silver/silicon-dioxide/silver nanosandwiches were grown by the oblique angle deposition technique. For normally incident light, these films present a negative-real refractive index (NRRI) over almost the entire visible regime, with quite high transparency and figures of merit, regardless of the orientation of the incident electric field. A broad distribution of nanosandwich sizes is responsible for the breadth of the NRRI spectral regime.

High Frequency Characteristics of Synthetic Antiferromagnetic Coupling FeCoN Sandwich Films

The soft magnetic FeCoN thin films and FeCoN/Ru/FeCoN sandwich-structured films were prepared by using DC magnetron sputtering system. The high frequency characteristics of the FeCoN films with FM/AFM/FM sandwich structures had been investigated. The effective magnetic anisotropy field ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</sub> ) of FeCoN sandwich films can be changed by adjusting the film structures, such as the thickness of the FM and AFM layers, and the roughness of the interface. Therefore, the ferromagnetic resonance frequency ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> ) of the FeCoN sandwich films can be tuned over a very wide range. The single-layer FeCoN films show a highest roll-off frequency of about 2.7 GHz, but that of the FeCoN sandwich films can be tuned over a very wide range from 3 GHz to beyond 8 GHz.

Phase Diagram of Antiferromagnet Film Sandwiches Between Ferromagnetic Surfaces

The Monte Carlo (MC) simulation is used to study the magnetic properties of a spin-1/2 Ising antiferromagnetic film sandwiches between two ferromagnetic surfaces. The influence of different exchange surface interactions on the phase diagram of such a film is studied. In the ordered phase, it is found that the antiferromagnetic layer of the film can change in ferromagnetic or ferrimagnetic phases, depending on the values of the surface, the perpendicular and the bulk magnetic couplings. Moreover, the sublattice magnetizations are computed as a function of temperature for a film of thickness n=10 and fixed values of magnetic couplings.