Optical Properties Of Indium Tin Oxide Research Articles

Variation of Nonlinear Refraction and Three-Photon Absorption of Indium-Tin Oxide Quantum Dot Thin Films and Solutions in Near Infrared Range.

We characterize the nonlinear optical properties of indium-tin oxide (ITO) quantum dots (QDs) in the IR range using the Z-scan method. We present results of three-photon absorption (3PA), third harmonic generation (3HG), and Kerr-effect-induced nonlinear refraction in ITO QDs. Z-scan measurements were carried out for the QDs solution, while 3HG was demonstrated using QD thin films. The Kerr-induced nonlinear refractive index was analyzed along the 800-950 nm range showing an increase in this parameter from -6.7 × 10-18 to -1.5 × 10-17 m2 W-1. At longer wavelengths (1000-1100 nm), the higher-order effects started to contribute to a nonlinear refractive index. The 3PA coefficient at 950 nm was measured to be 1.42 × 10-25 m3/W2. We discuss the peculiarities in the wavelength-dependent variation of the coefficient of nonlinear absorption responsible for 3PA in the range of 800-1150 nm. Third harmonic generation was analyzed in the 1200-1550 nm spectral range. The absolute value of 3HG conversion efficiency in the 150 nm thick film at the wavelength of laser radiation (1350 nm) was estimated to be ~10-5.

Photonic Characterisation of Indium Tin Oxide as a Function of Deposition Conditions.

Indium tin oxide (ITO) has recently gained prominence as a photonic nanomaterial, for example, in modulators, tuneable metasurfaces and for epsilon-near-zero (ENZ) photonics. The optical properties of ITO are typically described by the Drude model and are strongly dependent on the deposition conditions. In the current literature, studies often make several assumptions to connect the optically measured material parameters to the electrical properties of ITO, which are not always clear, nor do they necessarily apply. Here, we present a comprehensive study of the structural, electrical, and optical properties of ITO and showed how they relate to the deposition conditions. We use guided mode resonances to determine the dispersion curves of the deposited material and relate these to structural and electrical measurements to extract all relevant material parameters. We demonstrate how the carrier density, mobility, plasma frequency, electron effective mass, and collision frequency vary as a function of deposition conditions, and that the high-frequency permittivity (ϵ∞) can vary significantly from the value of ϵ∞ = 3.9 that many papers simply assume to be a constant. The depth of analysis we demonstrate allows the findings to be easily extrapolated to the photonic characterisation of other transparent conducting oxides (TCOs), whilst providing a much-needed reference for the research area.

Исследование влияния особенностей конструкции установки магнетронного распыления на электрические и оптические свойства пленок оксида индия-олова

The influence of the relative position of the magnetron and the substrate on the electrical and optical properties of the forming indium tin oxide (ITO) layers is demonstrated. The reasons for this behavior are considered and the role of oxygen in the onset of inhomogeneity of the properties of ITO films is shown. It is shown that, in the growth mode without additional oxygen addition, the resistivity of ITO films differs by an order of magnitude ((2−14)·10^−2 Ohm·cm) for different positions of the substrate on the substrate holder along the radius in the range of 0−14cm. In this case, absorption spectra are observed differences in the shape of the short-wavelength region of the spectrum. The addition of an insignificant (0.1sccm) amount of oxygen to the working chamber during the growth of the oxide leads to a significant increase in the homogeneity of the electrical and optical properties of ITO

XRD, UV-Vis-NIR and FT-IR Studies of ITO and Cr: ITO Thin Films Prepared by Electron Beam Evaporation Technique

The Indium-tin-oxide (ITO) and Cr doped ITO thin films were prepared using electron beam evaporation technique. The prepared thin films were subjected to structural and optical properties. From the XRD it was observed that the films were crystalline in nature with cubic structure. The crystallite size was calculated using Scherer's relation and found that it was about 25 nm. The optical transmittance and absorbance spectra were recorded using UV-Vis-NIR spectrophotometer. From these, the optical band gap of ITO and Cr:ITO thin films were found to be 4.0 ev and 3.97 eV, respectively. The Fourier transform-Infrared spectroscopy study showed the peaks at 292, 519, 804, 957, 114, 1387 and 2985 cm-1 which are characteristic of In-O bonds. Introduction. It is known that extensive work is being carried out on optical and electrical properties of wide band gap oxide semiconductors such as ZnO, TiO2, SnO2, In2O3, Cu2O etc. [1-7]. Among the other oxide semiconductors, In2O3 is the one of the best suited materials for many electronic applications. It is a transparent, degenerate n-type wide band gap semiconductor with cubic structure in which the optical and electrical properties can be varied by doping of tin (Sn) or creating off stoichiometry. In In2O3 lattice if 10% of Tin (Sn) is doped the resultant material indium-tin-oxide is called as ITO [8, 9]. Due to its peculiar properties of high electrical conductivity and high optical transmittance in visible region it finds numerous applications such as nano electronics, opto electronics, sensor devices, flat panel displays and energy storage devices [10-18]. However, the studies of magnetic properties of ITO and impurity doped ITO thin films are meager. Recently continuous efforts are being put on magnetic properties of ITO and doped ITO nanoparticles, thin films and nanostructures. At present, this paper has been focused more on the structural and optical properties of ITO and Cr:ITO thin films and magnetic studies will be carried out in the future.

Electrical and optical properties of indium-tin oxide (ITO) films by ion-assisted deposition (IAD) at room temperature

Indium-tin oxide (ITO) films have been traditionally deposited at elevated substrate temperature of 400°C to achieve low resistivity and high transmission. In some cases, films deposited at low substrate temperatures can be annealed at higher temperature to achieve lower resistivity. In this paper, thin films of ITO with various oxygen flow rates are prepared by ion-assisted electron beam evaporation at room temperature. Electrical, optical and structural properties of ITO thin films have been investigated with the function of oxygen flow rate, rate of deposition and layer thickness. Low resistivity of 7.5 × 10−4Ω-cm, high optical transmittance of 85% at wavelength 550 nm, optical band-gap of 4.2 eV and crystalline ITO films can be achieved at room temperature almost one order smaller than that prepared by other method.

Electrical and Optical Properties of Indium Tin Zirconium Oxide Films at Different Annealing Treatment Temperatures

Indium tin oxide (ITO) and indium tin zirconium oxide (ITZO) films were deposited on glass substrates at room temperature by magnetron sputtering technology with one or two targets. Electrical and optical properties of ITO and ITZO films by air-annealing treatment were contrastively studied. ITZO films provided with the preferential crystalline orientation change from (222) to (400) plane, as well as the increase in grain size and the decrease in surface roughness. As result, zirconium -doping remarkably improved the optical-electrical properties of the films deposited at room temperature. The resistivity of ITO and ITZO films showed the trend which includes first dropping and then rising, which was closely related with the variations of carrier concentration and mobility. ITZO films had high optical transmittance of above 80% at lower annealing temperature. ITZO films prepared by co-sputtering reveal better optical-electrical properties.

Electrical and optical properties of ITO and ITO/Cr-doped ITO films

In this paper we report on the effects of the insertion of Cr atoms on the electrical and optical properties of indium tin oxide (ITO) films to be used as electrodes in spin-polarized light-emitting devices. ITO films and ITO(80 nm)/Cr-doped ITO(20 nm) bilayers and Cr-doped ITO films with a thickness of 20 nm were grown by pulsed ArF excimer laser deposition. The optical, structural, morphological and electrical properties of ITO films and ITO/Cr-doped structures were characterized by UV–Visible transmission and reflection spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and Hall-effect analysis. For the different investigations, the samples were deposited on different substrates like silica and carbon coated Cu grids. ITO films with a thickness of 100 nm, a resistivity as low as ∼4×10−4 Ω cm, an energy gap of ∼4.3 eV and an atomic scale roughness were deposited at room temperature without any post-deposition process. The insertion of Cr into the ITO matrix in the upper 20 nm of the ITO matrix induced variations in the physical properties of the structure like an increase of average roughness (∼0.4–0.5 nm) and resistivity (up to ∼8×10−4 Ω cm). These variations were correlated to the microstructure of the Cr-doped ITO films with particular attention to the upper 20 nm.

The Role of Sputter Pressure in Influencing Electrical and Optical Properties of ITO on Glass

AbstractThin layers of indium tin oxide (ITO) were deposited onto glass substrates by RF magnetron sputtering with the pressure varying from 6 mTorr to 15 mTorr. The films were annealed in a reducing atmosphere at 500 °C for 30 minutes. Sheet resistance was determined by four-point-probe measurement. Resistivity, mobility, and carrier concentration were obtained by Hall effect measurements. Transmission of the films in the visible spectrum was determined by photospectrometry. The structure of the films was characterized by X-ray diffraction. X-ray photoelectron spectroscopy was used to determine the oxidation state of Sn, which was used to determine the fraction of active tin clusters. The effect of additional anneals was investigated. The results reveal that the lowest resistivity obtained was 1.69×10-4 -cm at 9 mTorr and the highest transmittance of 90% was obtained after a second anneal. However, the second anneal decreased the mobility and conductivity for high sputter pressures.

Development of transparent heat mirrors based on metal oxide thin film structures

The aim of this work is the preparation of RF sputtered indium–tin oxide (ITO) thin films for application as transparent heat mirrors. The heat mirrors are important elements for the photothermal solar energy conversion. In combination with moderate spectral selectivity of the solar absorbers they could increase the efficiency of the solar collector. The optical properties of ITO and double-layer ITO with titanium dioxide (TiO 2) structures in the visible and infrared ranges were investigated. The films were deposited on glass substrates by RF sputtering technique. Tin-doped indium, as well as titanium targets was used. The influence of the In–Sn target composition and the deposition parameters on the film properties were studied. The films' surface morphology and structure were investigated by SEM, TEM and XRD, the composition was studied applying electron probe microanalyzer (EPMA). The thicknesses of the films were determined by the laser ellipsometry method. The measurements in the infrared range were performed on Fourier transform infrared spectrophotometer (FTIR). The single layer ITO structures showed reflectance in the infrared range not exceeding 50% at longer wavelengths. The double layer structures with TiO 2 under layer showed increased reflectance in the infrared range with high visible transmittance reaching 85%.

The effect of the atmosphere on the optical properties of as-synthesized colloidal indium tinoxide

The optical properties of indium tin oxide (ITO) have often been explored when it is in theform of deposited thin films. In this study, a colloidal chemistry approach is taken toinvestigate the influence of the atmosphere on the optical properties of ITO nanoparticles.X-ray diffraction (XRD), transmission electron microscopy (TEM), absorption spectroscopyand photoluminescence (PL) were used to characterize colloidal ITO samples, synthesizedunder aerated and inert conditions, with the same composition. In both cases, theITO can be completely dispersed in a non-polar solvent without any evidenceof agglomeration. For the ITO made in air, the nanoparticle–solvent solutionexhibits a pale green color, and XRD and TEM indicate an average particle size of∼7 nm and small shrinkage in the lattice structure. When the ITO is synthesized under inertconditions, the solution turns blue, and XRD and TEM indicate an average particle size of∼8 nm and even less strain in the lattice than for the ITO synthesized under aeratedconditions. The change in color and lattice strain is attributed to the difference in oxygenvacancy concentration for the ITO nanoparticles synthesized under aerated and inertconditions, which exhibit different optical band gap values of 3.89 eV and 4.05 eV,respectively. Our work here shows that thin film deposition or sintering steps may not berequired for studying the optical properties of as-synthesized ITO nanoparticles.

Band gap shift in the indium-tin-oxide films on polyethylene napthalate after thermal annealing in air

Indium-tin-oxide (ITO) thin films on polyethylene napthalate (PEN) with high carrier concentration (∼1021∕cm3) have been grown by electron-beam deposition without the introduction of oxygen into the chamber. The electrical properties of the ITO films (such as, carrier concentration, electrical mobility, and resistivity) abruptly changed after annealing in the air atmospheres. In addition, optical transmittance and optical band gap values significantly changed after heat treatment. The optical band gap narrowing behavior is observed in the as-deposited sample because of impurity band and heavy carrier concentration. The influence of annealing in air on the electrical and optical properties of ITO∕PEN samples can be explained by the change in the free electron concentration, which is evaluated in terms of the oxygen content. Rutherford backscattering spectrometry and x-ray photoelectron spectroscopy analyses are used to determine the oxygen content in the film. Hall effect measurements are used to determine the dependence of electrical properties on oxygen content.

Effect of AC‐Powered Water Electrolysis on the Structural and Optical Properties of Indium Tin Oxide Thin Films

The changes in the structure and optical properties of indium tin oxide (ITO) thin films that were subjected to water electrolysis using an alternating current power source were investigated. X‐ray diffraction indicated that the film was reduced to metallic indium after the treatment. Scanning electron microscopy revealed that the film became porous after the treatment. These structural changes had led to a dramatic degradation in the optical properties of ITO. The electrochemical mechanism responsible for the changes was discussed.

Low temperature deposition of Indium tin oxide (ITO) films on plastic substrates

AbstractOrganic light emitting diodes (OLEDs) require a transparent conducting oxide (TCO) electrode for injection of charge carriers and the emitted light to come out. In order to exploit the full flexibility of organic semiconductor based large area electronic devices, the deposition of TCO on plastic substrates is essential, which prohibits high temperature processing. Therefore, low temperature deposition of Indium tin oxide (ITO) films is very important for flat panel displays and solar cells. Here we have carried out a systematic study of ITO deposition on plastic substrates using RF magnetron sputtering. For the optimization of structural, electrical and optical properties of ITO, various experiments such as X-ray diffractometer, transmission measurements, sheet resistance and AFM were employed. These properties were investigated as a function of substrate temperature, deposition time and RF power. From these experiments, we obtained a reasonably low sheet resistance (˜ 14;Ω / □) and high transmittance (˜75%) in the visible region on plastic substrates. We also observed that these films are not much affected by atmosphere and does not degrade with time. These ITO films deposited by RF magnetron sputtering on plastic substrates can be use as anode for flexible organic light emitting displays.

Calculation of the electronic and optical properties of indium tin oxide by density functional theory

Abstract Density functional theory (DFT) was used to calculate the bulk electronic and optical properties of indium tin oxide (ITO). The ITO model was constructed replacing indium atoms with tin atoms in the cubic unit cell of indium oxide. To allow more possibilities for tin atom substitution than afforded by the forty-atom primitive cell of indium oxide all eighty atoms of the unit cell were included in the stoichiometry (In32−xSnxO48) using periodic boundary conditions. A number of properties of ITO were calculated including the optical band gap, charge carrier density and plasma frequency. The dependence of the electronic and optical properties of ITO on a variety of parameters such as the tin content, cubic lattice parameter and the distance between adjacent tin atoms was investigated. The electronic and optical properties agreed well with experimental data and allowed insight into the origin of the electronic and optical properties of ITO.

ITO-on-top organic light-emitting devices: a correlated study of opto-electronic and structural characteristics

This paper reports on a complementary investigation of the structural and opto-electronic characteristics of top-emitting organic light-emitting diodes (OLEDs). The key point of such a procedure is the deposition of the indium tin oxide (ITO) transparent top electrode onto the organic films structure. This was achieved by RF sputtering under soft enough conditions so as to avoid any deterioration of the underlying organic layers (room temperature deposition, low plasma power density and minimal bombardment effect) as much as possible. The electrical and optical properties of ITO as a function of the deposition conditions are described first. Hall effect measurements show that ITO films can be grown at room temperature with a high mobility (40 cm2 V−1 s−1) and a carrier density exceeding 5 × 1020 cm−3. The surface roughness as a function of the plasma conditions was determined by AFM and can be as low as 1.2 nm. Hole only silicon/Al/poly(N-vinylcarbazole) (PVK)/poly(3,4)ethylenedioxythiophene (PEDOT)/sputtered ITO diodes were processed and characterized both structurally (high resolution TEM in cross section) and electrically. An excellent agreement between the interfacial ITO/PEDOT structure and the hole injection performance was evidenced. Glass/ITO/PEDOT/PVK/Alq/BCP/ITO top-emitting OLED were processed and characterized.

Interrelation between nanostructure and optical properties of oxide thin films by spectroscopic ellipsometry

Nanostructured thin oxide films of SnO 2, V 2O 5 and indium tin oxide (ITO) were deposited by conventional and plasma-assisted chemical vapor deposition (CVD, PECVD) on different substrates and at different temperatures. Optical properties of the films were determined by spectroscopic ellipsometry in the energy range 1.5–5.5 eV. A parameterized analysis, based on Lorentzian oscillators combined with the Drude model, along with Bruggeman effective-medium approximation (BEMA) modeling, was used to determine the optical constants of thin films independently from the reference dielectric functions of the bulk materials. In this way, correlation between the optical properties and nanostructure of thin films could be established. In particular, in order to discuss the dependence of optical constants on grain size, SnO 2 nanostructured films have been considered, using a parameterization based on a double Lorentzian oscillator. Nanocrystalline V 2O 5 thin films have demonstrated the correlation between optical constants (described by four Lorentzian oscillators) and crystalline/amorphous volume fractions. Finally, ITO thin film optical properties are described by a combination of a double Lorentzian oscillator with the Drude model; by this analysis, gradients in the structural and optical properties of ITO are demonstrated.

Spectroscopic ellipsometry characterization of indium tin oxide film microstructure and optical constants

Indium tin oxide (ITO) is a transparent conducting oxide in wide use today. ITO can be difficult to work with since this material displays a complicated (graded) microstructure, and the optical properties of ITO can vary widely with deposition conditions and post-deposition processing. For this reason it is common to characterize ITO films via optical measurements. However, accurate results are difficult to obtain due to the graded microstructure of the film introducing variations in the refractive index throughout the film thickness. Thus the typical ITO film does not have a single, well-defined set of optical constants due to grading in the microstructure. Several optical models for ITO will be presented which include the graded microstructure of the material and work reasonably well in fitting spectroscopic ellipsometry data for ITO film thickness, index grading, and optical constants. Since the film thickness, optical constants, and microstructure grading are all intermixed in the experimental data the issue of determining a unique best-fit optical model for ITO will also be discussed.

Low Earth orbit effects on indium tin oxide and polyester and comparison with laboratory simulations

Abstract Laboratory simulation of the low Earth orbit (LEO) environment using oxygen plasma ashers are discussed. Their effectiveness as space simulators are compared with LEO through analysis of indium tin oxide (ITO) thin films and bulk polyester exposed to both environments. Spectrophotometry and atomic force microscopy have been used to characterize optical and microstructural changes as a result of exposure to the simulated (oxygen plasma asher) and the actual space environment aboard shuttle flight STS-46. Results show that the low Earth orbit space environment is much harsher than the plasma asher on the optical properties of ITO as well as the surface roughness of polyester. On space-exposed samples, a significant shift in the ITO absorption edge is seen for fluences of 2 × 10 20 atoms cm -2 but not on films exposed in the asher. The surface roughness of polyester exposed in the asher increase by a factor of 5.5, while that of polyester exposed in space increases by a factor of 20 for the same atomic oxygen fluence. The directional nature and higher kinetic energy of atomic oxygen in LEO serves to erode polyester more than in the asher. The different results obtained in the asher for both ITO and polyester bring into question the suitability of using plasma ashers as space simulators for these materials.