Permittivity Of Films Research Articles

Coumarin 4 Laser dye/PVP Polymer/Al2O3 Nanoparticle Thin Films Induced by Er: YAG Laser Radiation

In this paper, thin films were made of 10-4 mol/l of Coumarin 4 laser dye dissolved in ethanol, 0.3 g of PVP polymer and 0.04 g of Al2O3 nanoparticles. The electrical properties such as dielectric constant, phase velocity of laser photons inside the film, the film permittivity and permeability, medium impedance, electrical conductivity, skin depth, the electrical response time, magnetic susceptibility and dielectric time have been studied for the prepared thin films at two different Er:YAG laser wavelengths of 1645nm and 1617 nm based on various laser powers in one time and with changed laser exposure periods in the other time. It is observed that the highest laser power consolidates each value of dielectric constant, dielectric time, electrical conductivity, the electrical response time, magnetic susceptibility and the permeability of film because of increasing the abundant energy in films within laser irradiation. The most important conclusion is that the electrical properties were much higher for the prepared thin films irradiated with 1645nm Er: YAG laser wavelength than for those irradiated with 1617nm laser wavelength.

“In-gap” Spectroscopy: Reflected-Wave Phase and Film Characterization

Optical methods that are used to characterize the state of a surface covered with films are based on the measurement of either the ratio between the complex reflection coefficients for mutually orthogonal light polarizations (ellipsometry) or the magnitudes of reflection coefficients themselves; afterward, the parameters of films such as their number, thicknesses, and transparencies can be determined by the fitting, while solving the corresponding inverse problem. In order to extend the set of quantities that can bemeasured experimentally, a method is proposed that allows the phase of the reflected light wave to be determined, by analyzing the spectral features for light reflected from a plane-parallel gap between the surface of analyzed specimen and the environment. In particular, the spectrum obtained, by using the “moving specimen” procedure, can be transformed into the spectral dependences of the magnitude and phase of the reflection coefficient. As a result, the inverse problem of finding the dielectric permittivity of a single-layer film is reduced to the solution of a linear matrix equation, which makes the proposed method more advantageous in comparison with the ellipsometric one, for which there is no direct relationships between the ellipsometric angles and the physical parameters of the film.

Obtaining of hydroxylated fullerenes Y@C82OX(OH)Y, Y2@C82OX(OH)Y, Y2C2@C82OX(OH)Y and electrophysical characteristic of composite film based thereon

The article presents, for the first time, the results of the research on composite film obtained from hydroxylated endohedral metallofullerenes (EMF) Y@C82, Y2@C82, with Y2C2@C82 and highest fullerenes as dopant. The composite film has been established to have electric conductivity and to be a ferroelectric with the value of residual polarization of ∼0.75 μC/cm2. The impedance spectroscopy of this sample allowed us to determine dispersion of dielectric permittivity and conductivity in the range of frequencies of 0.5 Hz–100 MHz. It is stated that the value of the high-frequency dielectric permittivity of films is ε′∞ = 2.8. However, with reduction in the electric field frequency, real and imaginary parts of ε increase to values ∼104–105. Such increase in dielectric permittivity is connected with increase in polarizing caused by accumulation of mobile electric charges (electrons of ions, protons) on boundaries of the structural defects of a film, which are divided by thin dielectric interlayers. The film is solid electrolyte with the ionic conductivity of ∼5 × 10−7 S/cm.

Inkjet Printing of SiO2 Hollow Spheres/Polyimide Hybrid Films for Foldable Low-k ILD

We demonstrate inkjet printing as a viable method for flexible interlayer dielectrics (ILDs) films with a low dielectric constant, excellent mechanical characteristics, and thermal properties in foldable organic light emitting diodes (OLEDs). SiO2 hollow spheres (SHSs)/polyimide (PI) hybrid films were printed by SiO2 coated polystyrene (PS) ink and PI ink. The relative permittivity of the hybrid films decreased from 3.45 to 1.87. The thermally stable PI fims maintained their weight below 500 °C from the TGA result. The dielectric constant and current density retained their properties after 50,000 cycles of bending at a 1 mm bend radius. We propose that the inkjet printing of SHSs/PI hybrid films described herein is a promising approach for flexible ILDs in foldable OLEDs.

Modeling the Dynamics of the Integral Dielectric Permittivity of a Porous Low-K Organosilicate Film during the Dry Etching of a Photoresist in O2 Plasma

Using an imitational cellular-automaton model, the structural degradation of a interlayer low-K dielectric during the plasma etching etching of a photoresist is studied. The dielectric represents a porous material based on SiOCH, whose integral dielectric permittivity depends on the percentage of carbon atoms on the pore walls and in the dielectric matrix. The period of etching is such that the removal of carbon (and, accordingly, degradation) is incomplete. The simulation is performed for 2 million steps of the automaton, which correspond to 2 s in the real process. During this period, the number of methyl groups does not exceed 20% of the initial value at the dielectric pore depth of 40 nm; in this case, the permittivity e increases from 2.5 to 2.84. Extrapolating to a longer time period (nearly 1 min) shows that the total fraction of СН3-groups is 9% of the initial value through the full depth of the material, while the final value of dielectric permittivity would correspond to 3.0–3.1. The results of the modeling agree with the experimental data described in the literature.

Novel lateral double-diffused MOSFET with folded silicon and high-permittivity dielectric breaking silicon limit

A novel folded-accumulation LDMOS (FALDMOS) employing high-permittivity (HK) material as the partial field dielectric (HK-FALDMOS) is proposed and investigated by simulation. The device features the high-k dielectric partially replacing conventional SiO2 as the field oxide covering partial drift region and the gate electrode extending to the drain electrode. In the ON-state, the majority-carrier accumulation effect of HK-FALDMOS is more intense than that of FALDMOS, which is attributed to the larger capacitance of high-k film with the same dielectric thickness. Besides, a higher doping concentration in drift region I is obtained due to the electric field modulation effect resulting from the employed high-k film, which further reduces the specific on-resistance (Ron,sp) of the drift region I. The breakdown voltage (BV) declines slightly with the increase of permittivity of high-k film. Simulation results show that the proposed HK-FALDMOS has best-in-class Ron,sp-BV performance (9.9 mΩ mm2 with BV of 44.9 V when the relative permittivity of high-k is 8), which breaks the silicon limit of LDMOS.

Ferroelectric, dielectric properties and electrical conduction mechanism of epitaxial B1-xDyxFeO3 (x = 0.05, 0.075, 0.1, 0.125) thin films prepared by pulsed laser deposition

We report that Dy doping can be used to enhance ferroelectric properties and reduce leakage current in (001) epitaxial Bi1-xDyxFeO3 (BDxFO) thin films where x = 0.05, 0.075, 0.1, 0.125. The 120 nm thin BDxFO films were prepared by pulsed laser deposition (PLD). Saturated ferroelectric hysteresis (P-E) loops were observed at room temperature with an increase in remanent polarization (Pr) with the increase in applied electric field and Dy concentration. The improved Pr in BDxFO films from x = 0.05 to 0.1 is attributed to reduction in oxygen vacancies with an increase in Dy content that prevents electric domain back-switching. However, BDxFO (x = 0.125) film exhibit leaky and unsaturated loop which may be due to the appearance of microscopic defects in the film. The leakage current in BDxFO films decreased by an order of magnitude as Dy content increased from x = 0.05 to 0.1. The detailed leakage current mechanism analysis is also presented. The results of positive up negative down (PUND) method confirmed that intrinsic polarization is due to ferroelectricity and not due to leakage. Relative permittivity (ɛ') of BDxFO films increased whereas dielectric loss tangent (tan δ) reduced as Dy content increased from x = 0.05 to 0.1.

High dielectric permittivity of HfO2-based films with (La,Bi,Nb) substitution

HfO2 thin films with elemental substitutions were formed by chemical solution deposition. Bi substitution distorts the HfO2 lattice and increases the polarization value. (Bi,Nb) substitution compensates the charge balance to prevent the formation of oxygen vacancies. The relative dielectric permittivity of the HfO2 film with 5 mol % La, 5 mol % Bi, and 5 mol % Nb substitution under an applied DC field was observed to be up to 78. The constriction of the polarization–electric field (P–E) curve disappears at a temperature lower than that where the dielectric permittivity is maximum. The phase transition from the paraelectric tetragonal phase to the ferroelectric orthorhombic phase causes the constriction of the P–E curve to disappear. We consider that the high dielectric permittivity was due to the phase-transition-related phenomena.

Millimeter wave (220 GHz–330 GHz) characterizations of carbon nanotube films

A carbon nanotube (CNT) film on a substrate is characterized at millimeter waves (220 GHz−330 GHz) by metal rectangular waveguide scattering parameters (S-parameters) measurements. The anisotropy of the CNT film is investigated for different orientations of the on-substrate CNT film. The standard Nicolson–Ross–Weir (NRW) approach has been adopted to extract the complex permittivity (εr=ε′-jε″) and permeability (μr=μ′-jμ″) of the on-substrate CNT film from the measured S-parameters. The effective medium theory is then applied to remove the impact of the substrate and characterize the intrinsic CNT film. The observed frequency independent and anisotropic behaviors of the CNT film are very promising indicators that this material could be invaluable for a range of millimeter-wave applications.

Permittivity and Loss Characterization of SUEX Epoxy Films for mmW and THz Applications

We present a systematic characterization of the dielectric permittivity and loss tangent of SUEX dry films for mmW and THz bands. Green and cured SUEX samples of varying thicknesses were studied using two complementary measurement techniques. First, the Nicolson–Ross–Weir technique was used in a two-port $TE_{10}$ waveguide environment for 90–140-GHz and 140–220-GHz bands. The samples were also characterized using a transmission-mode time domain THz spectrometer over the 90-GHz–2-THz band. Real part of permittivity and loss tangent were measured to be 3.08 and 0.057, respectively, for the green SUEX sample. Ultraviolet light curing reduces the permittivity and loss tangent down to 2.86 and 0.020, respectively. SUEX films can be easily laminated onto any substrate, eliminating the spin coating and long process optimizations that are required for conventional liquid resists. As such, SUEX is an easy-to-process alternative to commonly used epoxy-based resists, such as SU-8, while exhibiting similar dielectric permittivity and material losses.

Permittivity enhancement of transparent poly(vinylidene fluoride) nanocomposite films by loading titania-coated barium titanate nanoparticles

Barium titanate (BT) nanoparticles are coated by titania and modified by fluoroalkylsilane. The BT nanoparticles are incorporated into polyvinylidene fluoride (PVDF) films to obtain highly dielectric and transparent nanocomposite films at low filler loadings. Incorporation of BT nanoparticles having average sizes of 12 and 22 nm is performed. Incorporation of BT nanoparticles enhances the permittivity of PVDF films. Higher transparency of nanocomposite films is achieved by incorporating 12-nm nanoparticles compared to that by 22-nm nanoparticles. The polarisation mechanism in the nanocomposite films is examined using the Vo–Shi model. The result indicates that even a slight increase in the thickness of titania-coating layer on the BT nanoparticles increase the permittivity of the nanocomposite films. Comparison of the measured and calculated permittivities showed that the incorporation of BT nanoparticles coated with titania provides a practical approach to create transparent nanocomposite films having high permittivity.

Controlling the Plasmonic Properties of Ultrathin TiN Films at the Atomic Level

By combining first-principles theoretical calculations and experimental optical and structural characterization such as spectroscopic ellipsometry, X-ray spectroscopy, and electron microscopy, we study the dielectric permittivity and plasmonic properties of ultrathin TiN films at an atomistic level. Our theoretical results indicate a remarkably persistent metallic character of ultrathin TiN films and a progressive red shift of the plasmon energy as the thickness of the film is reduced, which is consistent with previous experimental studies. The microscopic origin of this trend is interpreted in terms of the characteristic two-band electronic structure of the system. Surface oxidation and substrate strain are also investigated to explain the deviation of the optical properties from the ideal case. This paves the way to the realization of ultrathin TiN films with tailorable and tunable plasmonic properties in the visible range for applications in ultrathin metasurfaces and nonlinear optics.

Fabrication and characterisation of substrate-free PZT thick films

This paper reports the preparation of dense and substrate-free PZT thick films. Electrohydrodynamic jet deposition and sol infiltration were utilized to produce dense PZT thick film, then wet chemical etching was employed to successfully remove the silicon substrate. Subsequently, a pure PZT thick film having a thickness of 14 µm without substrate was produced. The piezoresponse force microscopy technique was used to examine the piezoelectric constant (d33, f), it was found that the d33 was increased from 71 pm V−1 to 140 pm V−1, having a double increase. It was also observed that the remnant polarization (Pr) and relative permittivity (εr) of PZT film were distinctly improved after the removal of silicon substrate. The experimental result shows that the substrate clamping had great effects on the electrical properties of PZT films and its effect value was evaluated. In addition, the systematic theoretical analysis of the substrate clamping on film was deeply studied. The theoretical analysis agrees well with the experiment results, which can be used to estimate the effect value caused by the substrate clamping.

Vibrational, thermal and ion transport properties of PVA-PVP-PEG-MeSO4Na based polymer blend electrolyte films

Polyvinyl alcohol (PVA)-polyvinyl pyrrolidone (PVP)-polyethylene glycol (PEG) based polymer blend electrolyte films have been prepared by varying the Sodium methylsulfate (MeSO4Na) salt, in different % ratio using solution cast technique. Various techniques i.e. ATR-FTIR, TGA, DSC and AC Impedance spectroscopy have been used to characterize the prepared samples. ATR-FTIR result shows the complexation of MeSO4Na salt with PVA-PVP polymer blend. TGA results show the thermal stability of polymeric blend electrolyte changes with MeSO4Na content in PVA-PVP based polymer blend and also formation of miscible blend. DSC analysis reveals that single glass transition temperature (Tg) and melting temperature (Tm) changes with increasing MeSO4Na content. The dielectric relaxation frequency, fr has been found to increase with temperature in PVA-PVP-PEG-20MeSO4Na. Ionic conductivity and dielectric relaxation frequency vs. 1/T plots for PVA-PVP-PEG-20MeSO4Na based polymeric films follows the Arrhenius behavior. The maximum conductivity of 1.67 × 10−5 S/cm has been found for sample PVA-PVP-PEG-20MeSO4Na at room temperature. AC conductivity vs. frequency (Hz) curves was obtained for different PVA-PVP based polymer blend with respect to salt concentrations and temperatures. Dielectric permittivity and electric modulus of the polymeric films have been studied for various frequencies. Scaling i.e. σ/σ0 vs. ω/ωo has been done for PVA-PVP-PEG-20MeSO4Na polymer blend electrolyte.

Characterization of amorphous silica nanofiller effect on the structural, morphological, optical, thermal, dielectric and electrical properties of PVA–PVP blend based polymer nanocomposites for their flexible nanodielectric applications

The biodegradable polymers blend matrix of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) blend (50/50 wt%) dispersed with amorphous silica (SiO2) nanoparticles based polymer nanocomposite (PNC) films (i.e., (PVA–PVP)–x wt% SiO2; x = 0, 1, 3 and 5) were prepared by the aqueous solution-cast method. These PNC films were characterized by employing the X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, differential scanning calorimetry and dielectric relaxation spectroscopy techniques. It is found that the dispersion of nanosize SiO2 particles in the PVA–PVP blend matrix reduces the size of PVA crystallites and, turns the surface morphology from smooth into porous and relatively rough for the PNC films. The SiO2 interaction with polymer structure significantly alters the polymer–polymer interactions, reduces the optical band gap and the glass phase transition temperature, and enhances the melting phase transition temperature of the polymer blend films. The dielectric permittivity of the PNC films initially decreases with the increase of SiO2 contents up to 3 wt%, but at 5 wt% SiO2 concentration it is found nearly same as that of the pristine polymer blend matrix. The ac conductivity of these PNC films increases with the increase of frequency according to the power law relation. The dielectric permittivity exhibits non-linear increase with the increase of temperature of the PNC film whereas its dc conductivity obeys the Arrhenius behaviour. The dielectric and electrical properties of these PNC films realize their suitability as low-permittivity and low loss novel nanodielectrics for the substrate and insulator in the development of various microelectronic and organo-electronic devices.

Optical and electrical properties of ultra-thin indium tin oxide nanofilms on silicon for infrared photonics

Optical and electrical properties of indium tin oxide (ITO) films on Si substrates in the thickness range from 10 nm to 100 nm were investigated. Spectroscopic ellipsometry was used to obtain the complex permittivity of the ultra-thin films in the spectral range from visible to long-wave infrared. It was found that as the thickness decreases, the Drude component of the electric permittivity becomes vanishingly small, eventually leaving only positive permittivity values. This coincides with an epsilon-near-zero wavelength red-shift from 1.5 to 2.1 um for the films that retain negative permittivities. Hall measurements were conducted to determine that the mobility of the films correspondingly decreased from 35 cm2/Vs to single digits. This decreasing mobility is the result of a non-electrical dead layer that was determined to be ~14 nm thick, which occurs at the ITO/Si interface and is due predominately to interfacial defects. The thickness of this dead layer depends on the deposition process and substrate. The optical and electrical properties of ultra-thin ITO films are useful for the precise design of infrared plasmonic modulators, perfect light absorbers and other photonic devices.

Permittivity of Ge, Te and Se thin films in the 200–1500 nm spectral range. Predicting the segregation effects in silver

Optical properties of well-known bulk materials can be significantly modified by decreasing dimensions to nm-size. Using Molecular Beam Epitaxy (MBE) and e-beam Physical Vapour Deposition (PVD) we have fabricated 20–30 nm-thick amorphous Ge, Te and Se films. The permittivities of investigated layers have been extracted from measurements of the Ψ and Δ ellipsometric azimuths. We found that for all of the investigated films, the intensity of all bands in the permittivity spectrum is smaller than for bulk materials or thick (> 100 nm) films. Using the acquired optical constants along with the permittivity of a 20 nm-thick silver film, we have applied the Maxwell-Garnett equation to predict the permittivities of a silver film with Ge, Se or Te segregated in its structure. Implementing the parameters of 20 nm-thick Ge results in an 81 nm redshift of the segregation-induced band with respect to the experimental value, while implementing the parameters of 2 nm-thick Ge film results in a 95 nm blueshift of this band.

Enhanced dielectric thermal stability and permittivity of flexible composite films based on BaTiO3 nanoparticles highly filled PVDF/PAN blend nanofibrous membranes

Polymer film capacitors with high stability and reliability at elevated temperatures are promising for next‐generation power electronic systems and hybrid electric vehicles. In this work, sandwich‐structured composite films with good dielectric thermal stability were fabricated based on hybrid membranes of poly(vinylidene fluoride)/polyacrylonitrile blend nanofibrous skeleton highly filled with BaTiO3 nanoparticles. Composite films with 64.7 vol% BaTiO3 nanoparticles in the core layer exhibited high permittivity (38.1) and low loss (0.046) at 1 kHz and room temperature, and the dielectric permittivity and loss were only slightly increased to 41.5 and 0.08, respectively, at 120°C. Good dispersion and high loading of BaTiO3 nanoparticles in the composites films contributed to enhanced dielectric thermal stability and permittivity. Moreover, the composite films showed good flexibility, which could be ascribed to its sandwich‐structure. Our work paves a generic way to fabricate flexible composite films with excellent dielectric thermal stability via high loadings of ceramic nanoparticles. POLYM. COMPOS., 39:E1841–E1848, 2018. © 2018 Society of Plastics Engineers

Percolative multi-susceptible PVDF/NZFO composite films with triply controlled high dielectric and magnetic properties

Flexible multi-field susceptible films with remarkable properties and high data storage characteristics are promising in modern electronics. In this work, the percolative Ni0.5Zn0.5Fe2O4 (NZFO)/polyvinylidene fluoride (PVDF) composite films with both high permittivity and significant magnetic properties are prepared by dip coating on ITO/glass substrates. The highest permittivity of 74 is achieved with the NZFO volume ratio close to the percolation threshold, which is 20 times higher than that of pure PVDF. Meanwhile, the dielectric loss is kept below 0.1. The saturation and remanent magnetizations of composite films are 42.04 and 5.70 emu/g and the permeability is ∼3.105, reaching 60%–80% of those in the single phase NZFO. Detailed analysis shows that the high permittivity of the composite film is triply controlled simultaneously by the intrinsic characteristic of the PVDF phase, Kirkpatrick's hybridization model and microcapacitor behavior. It will be of broad interest to control both high dielectric and magnetic properties at the same time of many other flexible and susceptible storage devices.

Studies on Conducting Polymer Blends: Synthesis and Characterizations of PVA/PVP Doped with CaCl₂.

Calcium ion conducting polymer blend electrolyte films based on PVA/PVP complexed with CaCl2 have been prepared by solution casting technique. The structural changes of the polymer blends have been studied by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. XRD and FT-IR studies confirmed the complex formation of polymer blends. Electrical conductivity was calculated with impedance analyzer within the frequency range 42 Hz-1 MHz and in the temperature range 303 K-340 K. The higher electrical conductivity value of 1.704 × 10-4 Scm-1 was observed for 50PVA:50PVP:15 wt% CaCl2 concentration at room temperature. The magnitude of electrical conductivity was increased with the increase in the salt concentration as well as temperature. The electrical permittivity of the polymer films have been studied for various temperatures.