Dielectric Constant Of Thin Films Research Articles

Surface plasmon resonance spectrometer in the double prism configuration: Fast characterization of the thickness and dielectric constant dispersion of thin films

Surface plasmon resonance (SPR)-based sensors are widely used to measure thin film thickness, material dielectric constants, biomolecular interactions, and more. However, conventional monochromatic setups limit the simultaneous determination of dielectric constant dispersion and film thickness. To address this, we developed a fully automated wavelength-resolved SPR using a double-prism Kretschmann configuration. Combining this setup with a computational approach based on Fresnel equations and the Nelder-Mead optimization method, we introduced a novel technique to simultaneously determine the dispersion (520–1000 nm) of the real and imaginary components of the dielectric constant of thin films directly from SPR curves. As far as we know, this is the first time an SPR spectrometer has accomplished such a remarkable achievement. As a proof of concept for biosensor applications, we determined the thickness and dielectric constant dispersion of gold and bovine serum albumin thin film. These thicknesses were validated through atomic force microscopy, and the dielectric constants aligned closely with literature values obtained by ellipsometry. The developed SPR system enables precise measurements of these parameters within a short time (10 minutes), paving the way for future applications in advanced sensors and biosensors.

Düşük derişimli öncü çözeltilerle hazırlanan CdX (X=Se, S) ince filmlerinin temel optiksel parametrelerinin belirlenmesi

CdSe and CdS thin films, one of the II-VI group semiconductor compounds, were successfully grown by electrochemical deposition method using low concentrations of precursor solutions. Optical properties of the fabricated thin films were investigated in the 300 – 850 nm wavelength range. The absorption coefficients of CdSe and CdS thin films were found to be as 5.8 x 105 m-1 and 8.9 x 106 m-1, respectively, and direct energy band gaps these thin films were determined 2.72 eV and 2.75 eV. While the average transmission value of the CdSe was 85%, that of the CdS was 8%. Additionally, extinction coefficient values of the CdSe and CdS thin films were defined as 0.033 and 0.51, respectively and refractive index values of these were determined as 1.14 and 1.35. Besides, optical dielectric constants of thin films were examined. While the real dielectric constant, imaginary dielectric constant, dielectric loss and optical conductivity values of the CdSe were 1.24, 0.05, 0.004 and 1.38x1014, those of CdS thin film were 1.51, 0.94, 0.64 and 2.49x1015.

Резонатор для измерения диэлектрической проницаемости тонких плёнок.

Резонатор для измерения диэлектрической проницаемости тонких плёнок.

Optical, electrical, structural and magnetic properties of BiSe thin films produced by CBD on different substrates for optoelectronics applications

BiSe thin films have been grown on substrates as PMMA, ITO, glass and Si wafer by using chemical bath deposition (CBD) method. Deposition temperature and time and pH are kept to be constant during the production of the thin films. The thickness of BiSe thin films, which are produced on ITO, glass, PMMA and Si wafer substrate are 513, 468, 1039 and 260 nm, respectively. According to GAXRD results, the films, which are grown on glass and PMMA substrate, have amorphous structure, but, the films, which are grown on ITO and Si wafer substrate, have peaks of Bi2Se3 crystal. Grain sizes, crystallization number per unit area and dislocation density for ITO and Si wafer substrate are calculated as 112.40 nm and 43.04 nm; 2.25 × 10−5 and 7.91 × 10−5 (1/nm2); 40.11 × 10−5 (1/nm2) and 53.96 × 10−5 (1/nm2), respectively. The contact angles and critical surface tension of distilled water, ethylene glycol, formamide and diiodamethane liquids for thin films grown on glass, ITO, PMMA and Si wafers were obtained by the Zisman method. The % transmittance and % reflectance values of thin films grown on glass, ITO, PMMA are calculated as % T: 79.90, 92.76 and 67.37; % R: 6.18, 2.07 and 10.59, respectively. Eg values of thin films grown on glass, ITO, PMMA are calculated as Eg = 1.92; 2.18; 1.60 eV. The extinction coefficients, refractive indexes and relative dielectric constants of thin films grown on glass, ITO, PMMA are calculated as k = 0.007; 0.002 and 0.012; n = 1.65; 1.34 and 1.96; ε1 = 0.271; 0.083 and 0.528 respectively. Sheet resistance, hall mobility, sheet carrier densities, bulk carrier densities and conductivity types for glass, ITO, PMMA and Si are 6.52 × 107, 6.65 × 101, 1.09 × 108 and 6.45 × 102 (Ω/cm2); 2.38, 1.21 × 10−1, 5.34 and 1.52 (cm2/V.s); 4.01 × 1010, 7.71 × 1017, 1.06 × 1010 and 6.34 × 1015 (cm−2); 4.58 × 1014, 1.50 × 1022, 1.02 × 1014 and 2.89 × 1020 (cm−3); p, n, p and p, respectively. In addition, I–V characteristics and changes of magnetoresistance values versus magnetic field of the thin films are obtained by Van der Pauw method and HEMS.

Nondestructive method of thin-film dielectric constant measurements by two-wire capacitor

We suggest the nondestructive method for determination of the dielectric constant of substrate-deposited thin films by capacitance measurement with two parallel wires placed on top of the film. The exact analytical formula for the capacitance of such system is derived. The functional dependence of the capacitance on dielectric constants of the film, substrate, and environment media and on the distance between the wires permits to measure the dielectric constant of thin films for the vast set of parameters where previously proposed approximate methods are less efficient.

Effect of substrate temperature on the physical properties of co-evaporated Sn2S3 thin films

We report the deposition of tin sulfide (Sn2S3) thin films by co-evaporation technique at different substrate temperatures. The influence of substrate temperature on the structural and optical properties of the thin films is investigated. X- ray diffraction (XRD) analysis and Micro-Raman studies confirm the formation of Sn2S3 phase. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) are used to examine the surface morphology. The transmission spectra of the deposited Sn2S3 thin films have been recorded in the wavelength range of 200–3000nm using UV–vis-NIR spectrometer. Film thickness (d) and optical constants such as refractive index (n), extinction coefficient (k), real (ε1) and imaginary (ε2) parts of the dielectric constants of thin films are estimated from the optical transmittance. The optical band gaps of the deposited films at different substrate temperatures are in the range of 1.46–1.64eV. Hall effect measurements confirm the n-type nature of the as-prepared Sn2S3 thin films.

Finite Conductivity Effects in Electrostatic Force Microscopy on Thin Dielectric Films: A Theoretical Model

A study of the electrostatic force between an Electrostatic Force Microscope tip and a dielectric thin film with finite conductivity is presented. By using the Thomas-Fermi approximation and the method of image charges, we calculate the electrostatic potential and force as a function of the thin film screening length, which is a magnitude related to the amount of free charge in the thin film and is defined as the maximum length that the electric field is able to penetrate in the sample. We show the microscope’s signal on dielectric films can change significantly in the presence of a finite conductivity even in the limit of large screening lengths. This is particularly relevant in determining the effective dielectric constant of thin films from Electrostatic Force Microscopy measurements. According to our model, for example, a small conductivity can induce an error of more than two orders of magnitude in the determination of the dielectric constant of a material. Finally, we suggest a method to discriminate between permittivity and conductivity effects by analyzing the dependence of the signal with the tip-sample distance.

Dielectric Property of PZT Thin Films Doped with PMnN

The high piezoelectricity and high mechanical quality factor thin films are very important for the fabrications of micro devices. The Pb(Zrx,Ti1-x)O3(PZT) thin films own high piezoelectricity, however, its mechanical quality factor is small. The proper doping of Pb(Mn1/3,Nb2/3)O3(PMnN) will perfectly improve the mechanical quality of the films. However, the doping of PMnN will change the dielectric property of PZT thin films, and so it’s very necessary to investigate the dielectric property of PZT thin films doped with different ratio of PMnN. In this paper, the Pb(Mn1/3,Nb2/3)O3- PbZrO3-PbTiO3(PMnN-PZT) thin films with different doping ratio of PMnN are deposited by the magnetron sputtering method, and the X-ray diffraction is applied to analyze the structure of thin films, and the relative dielectric constant are characterized by the LCR testing system. The results show that the PMnN-PZT thin films with smaller doping ratio than 20% exhibit polycrstal structure, and the dielectric constant of thin films increase with the doping ratio of PMnN sharply, especially the doped PMnN is smaller than 6 mol percent. All the dielectric constants decrease with the testing frequency, and which have little change if the testing frequency is larger than 2.5kHz.

The use of artificial neural networks in electrostatic force microscopy

The use of electrostatic force microscopy (EFM) to characterize and manipulate surfaces at the nanoscale usually faces the problem of dealing with systems where several parameters are not known. Artificial neural networks (ANNs) have demonstrated to be a very useful tool to tackle this type of problems. Here, we show that the use of ANNs allows us to quantitatively estimate magnitudes such as the dielectric constant of thin films. To improve thin film dielectric constant estimations in EFM, we first increase the accuracy of numerical simulations by replacing the standard minimization technique by a method based on ANN learning algorithms. Second, we use the improved numerical results to build a complete training set for a new ANN. The results obtained by the ANN suggest that accurate values for the thin film dielectric constant can only be estimated if the thin film thickness and sample dielectric constant are known.PACS: 07.79.Lh; 07.05.Mh; 61.46.Fg.

Ultrahigh dielectric constant of thin films obtained by electrostatic force microscopy and artificial neural networks

A detailed analysis of the electrostatic interaction between an electrostatic force microscope tip and a thin film is presented. By using artificial neural networks, an equivalent semiinfinite sample has been described as an excellent approximation to characterize the whole thin film sample. A useful analytical expression has been also developed. In the case of very small thin film thicknesses (around 1 nm), the electric response of the material differs even for very high dielectric constants. This effect can be very important for thin materials where the finite size effect can be described by an ultrahigh thin film dielectric constant.

Fabrication and Electrical Properties of P(VDF-TrFE)/Bi<sub>3.5</sub>Nd<sub>0.5</sub>Ti<sub>3</sub>O<sub>12</sub> Bi-Layer Composite Ferroelectric Thin Films

The microstructure and electrical properties of P(VDF-TrFE)/Bi3.5Nd0.5Ti3O12bi-layer composite ferroelectric thin films deposited on Pt/Ti/SiO2/Si using two successive spin coatings were investigated. It shows the pores in Bi3.5Nd0.5Ti3O12(BNT) films were effectively suppressed by the presence of P(VDF-TrFE) copolymer films by SEM. The ferroelectric, leakage and dielectric properties of the thin films with different thickness ratio of P(VDF-TrFE) and BNT thin films were measured. With increasing the thickness of P(VDF-TrFE), the remnant polarization, coercive electric field, leakage current density and dielectric constant of thin films were all decreased (except pure P(VDF-TrFE) thin film). Results indicate that the key electrical properties were improved effectively by a little loss of the remnant polarization, which infers potential application in the filed of ferroelectric memory.

Sol–gel deposited SiO 2 and hybrid low dielectric constant thin films

The paper presents the comparative analysis of effect of hydrochloric (HCl), hydrofluoric (HF) acid catalyst and organic material methylmethacrylate (MMA) on dielectric constant of thin films. The dielectric constant of thin film obtained by using HCl catalyst is 3.63 which have been successfully reduced to 2.97 for hybrid thin films via incorporation of carbon. The deposited low k dielectric thin films observed to have good adhesion with p-silicon substrate and hence pertinent for interlayer dielectric (ILD) in ultra-large scale integrated (ULSI) circuits applications. The deposited films have been characterized by ellipsometer for refractive index, further material compositions have been studied by using Fourier transform infrared (FTIR) spectroscopy and energy dispersive spectroscopy (EDAX).

Electrical Reliability of Solgel Barium Titanate Films on Copper Foils for Organic Package Integration

AbstractThere is an increasing need for integrating high dielectric constant ceramic thin film components in organic and 3D IC packages to lower the power-supply impedance at high frequencies and supply noise-free power to the ICs. Sol-gel approach is very attractive for high density capacitors because of its ability to precisely control the composition of the films and the ease of introducing dopants to engineer the dielectric properties such as breakdown voltages and DC leakage characteristics. Thin films on copper foils lend themselves to organic package integration with standard foil lamination techniques used in package build-up processes. However, fabrication of thin film barium titanate on copper foils is generally affected by process incompatibility during crystallization in reducing atmospheres, leading to poor crystallization, oxygen vacancies and copper diffusion through the film that degrades the electrical properties.This paper focuses on the dielectric properties and electrical reliability of thin films on copper foils. Thin film (300-400 nm) embedded capacitors with capacitance density of 2 μF/cm2, low leakage current and high breakdown voltage were fabricated via sol-gel technology and foil lamination. To lower the leakage current, the chemical composition was altered by incorporating – 1.) Excess barium 2.) Acceptor dopants such as Mn. Both approaches lowered the leakage current compared to that of pure barium titanate. SEM analysis showed enhanced densification and refined grain structure with chemistry modification. The films showed good stability in leakage currents at 150 C with an applied field strength of 100 kV/cm, demonstrating the electrical reliability of these films.

Quantitative dielectric constant measurement of thin films by DC electrostatic forcemicroscopy

A simple method to measure the static dielectric constant of thin films with nanometricspatial resolution is presented. The dielectric constant is extracted from DCelectrostatic force measurements with the use of an accurate analytical model.The method is validated here on thin silicon dioxide films (8 nm thick, dielectricconstant∼4) and purple membrane monolayers (6 nm thick, dielectricconstant∼2), providing results in excellent agreement with those recently obtained by nanoscalecapacitance microscopy using a current-sensing approach. The main advantage of the forcedetection approach resides in its simplicity and direct application on any commercialatomic force microscope with no need of additional sophisticated electronics, thus beingeasily available to researchers in materials science, biophysics and semiconductortechnology.

Determination of thickness and dielectric constant of thin films by dual-wavelength light beaming effect of a metal nanoslit

We report simultaneous determination of the thickness and dielectric constant of thin films by dual-wavelength (488 and 645 nm) light beaming effect of a metal nanoslit in an optically thick metal film flanked by periodic corrugations. The feasibility of the method is confirmed by the finite-difference time-domain simulations, and sensitivities of 72°/RIU (RIU, Refractive Index Unit) at 488 nm and 32°/RIU at 645 nm are obtained, respectively. The unambiguous determination of the thickness and dielectric constant of the samples by just one-step measurement as well as the compact optical geometry of the structures suggests a highly portable and robust novel sensing technology.

Measurement of Dielectric Constant of Thin Film Materials at Microwave Frequencies

To determine the dielectric constant of thin film materials with thickness around one or several microns at microwave frequencies, a novel method based on modified cavity perturbation theory is presented. Corresponding measurement fixture is composed of Agilent 8720ES VNA, a rectangular cavity with small slots, and crystal slices used as the carriers of thin films. By measuring the shift in resonant frequency, the dielectric constant of thin film can be determined. 810 nm thick (Mg0.95Ca0.05)TiO3 thin film deposited by RF magnetron sputtering was used as sample to verify the feasibility of this technique, and the measured dielectric constant is 21.1, which is close to that of the bulk material. The measurement error of this method is about 6%, which mainly comes from the measurement errors of resonant frequencies and the thickness of thin film. This error can be reduced by using a cavity with higher Q, or by using thin film samples with larger dielectric constant or with thickness bigger than 1 micron. Experimental results show that the method presented in this paper is feasible and has good accuracy for dielectric thin film.

Localized Plasmons Seen by Propagating Surface Plasmons: Unique Determination of Their Dielectric Response

The plasmonic resonance that occurs when metal spheres interact with a metal surface over a thin gap is investigated by multiwavelength surface plasmon spectroscopy in Kretschmann configuration. A strategy is proposed to determine the polarizability per unit area from those experiments, and the limitations of this analysis are discussed. This approach completely avoids the ambiguity in the determination of thickness and dielectric constant of thin films in surface plasmon spectroscopy. Since it is intimately connected with the density of objects on the surface, the polarizability per unit area represents a very intuitive physical quantity that can be used to characterize the optical response of a layer. We show that results from standard extinction experiments are reproduced by this approach with higher information content and significantly increased signal-to-noise ratio.

Characterization on polymerized thin films for low- k insulator using PECVD

Plasma polymerized cyclohexane and TEOS hybrid thin films have been deposited on silicon substrates at room temperature with varying RF power by plasma-enhanced chemical vapor deposition (PECVD) method. As-grown thin films were annealed in vacuum. Cyclohexane monomer was utilized as organic precursor and TEOS monomer as inorganic precursor. Hydrogen and argon were used as bubbler and carrier gases, respectively. The as-grown plasma polymerized hybrid thin films were analyzed by FT-IR spectroscopy, hardness and modulus measurements, and electrical properties. Annealed hybrid thin films were also analyzed. The dielectric constant of thin films increases with increasing plasma power.

Structure and Dielectric Properties of Zn Doped PST Thin Films Prepared by Sol-Gel Method

(PbySr1-y)ZnxTi1-xO3-x thin films were prepared on ITO/glass substrate by sol–gel process using dip-coating method. The phase structure, morphology, and dielectric properties of thin films were investigated by XRD, SEM and impedance analyzer, respectively. The perovskite phase structure was exhibited in the Zn-doped PST thin films. The formation ability of the thin films of the perovskite phase and its grain size decreased with the increase in doping Zn. The dielectric constant of the thin film was influenced by oxygen vacancies which could be controlled by Zn doping.

Self Polarization in Pb(Sc1/2Ta1/2)O3 Relaxor Thin Films: Impact on the Dielectric and Piezoelectric Response

The phenomenon of “self-polarization” was studied in chemical solution derived Pb(Sc1/2Ta1/2)O3 (PST) thin films on Pt/Si substrates. PST films exhibited field induced pyroelectric coefficients of 300 µC/(m2 K), with a detectivity figure of merit Fd=1.5×10-5 Pa-1/2 at 100 kV/cm bias fields. The piezoelectric coefficient d33 was found to saturate at a value of 60 pm/V at 100 kV/cm applied field and the electrostriction coefficient Q33 was found to be ∼0.025 m4/C2. The presence of self polarization was confirmed by piezoelectric and pyroelectric activity under zero applied bias fields, resulting in a pyroelectric coefficient of 50 µC/(m2 K), or an equivalent internal field of ∼25 kV/cm. The impact of this internal bias field on the dielectric constant at temperatures near the dielectric maximum corresponds to a ∼10% reduction in the dielectric constant. It is concluded that the “self-polarization” observed in relaxor PST films cannot be the origin of the order of magnitude reduction in the dielectric constant of thin films as compared to ceramics.