Optical Properties Of ITO Films Research Articles

Effect of oxygen flow on electrical and optical properties of ITO films synthesized by magnetron sputtering method

The tin-doped indium oxide thin films were synthesized by DC magnetron sputtering on the surface of polished silicon samples and glass slides in a mixed argon-oxygen atmosphere. The other deposition parameters: operating pressure, magnetron power and substrate rotation speed were kept constant. Thickness and density of thin films were measured by X-ray Reflectometry. The effects of oxygen flow rate and substrate temperature on the optical and electrical properties were investigated. The electrical properties (resistivity, Hall mobility and charge concentration) of the thin films were measured by the Van der Pauw method using the Hall effect. The minimum value of resistivity 0.52 × 10-3 Ohm·cm, and maximum charge mobility 28 cm2V-1s-1 was achieved at an oxygen proportional gas mixture of 2.6% (0.71 sccm). The transmission spectra of the films were measured in the wavelength range from 300 to 1100 nm. The transmittance of all films exceeds 75% in the visible and near-infrared spectral ranges. It was found that increasing the oxygen flow rate and heating of the substrate up to optimal value 150°C led to an increase in the crystallinity of the films and, consequently, to an increase in the Hall mobility and the transmittance.

Structial, Electrophysical, and Optical Properties of ITO Films Produced by the Modified CVD Method

Structial, Electrophysical, and Optical Properties of ITO Films Produced by the Modified CVD Method

Thickness dependency of PVA on the transition from saturable absorption to reverse saturable absorption of ITO films

The transition from saturable to reverse saturable absorption of ITO films was realized by composite with PVA polymer. The effects of different thickness of PVA buffer layer on the structure and optical properties of ITO films were investigated. XRD results show that PVA buffer layer has influences on the preferred orientation of ITO films and the wavelength range of dielectric constant of ENZ can be adjusted from 1308 to 2023 nm. In these nanocomposites, a transition from saturable absorption to reverse saturable absorption was observed varying with the PVA buffer layer thickness. The β for ITO/PVA composites materials can be regulated from −5.89 × 108 to 4.37 × 108 cm/GW. The nonlinear optical properties of ITO/PVA composites can be ascribed to the charge transition, the interaction between ITO, the changes of materials structure, morphology caused by recombination and synergistic competitive effect between ITO and PVA films.

Electrical and optical properties of ITO films annealed at high humidity

Electrical and optical properties of ITO films annealed at high humidity

Towards high quality ITO coatings: The impact of nitrogen admixture in HiPIMS discharges

The paper reports controlled deposition of optically transparent and electrically conductive ITO films prepared by a combination of rf (13.56MHz) and High Power Impulse Magnetron Sputtering (HiPIMS) systems without any post deposition thermal treatment/annealing. It is shown that (i) reactive admixture of N2 gas to the process and (ii) pressure in the deposition chamber enable to optimize optical properties of ITO films. Furthermore, the changes of electrical resistivity were observed, too. The variation of these ITO properties is attributed to change of crystalline structure measured by XRD methods.

Microstructure, electrical and optoelectronic characterizations of transparent conductive nanocrystalline $${\mathbf{In}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{3}}$$ In 2 O 3 :Sn thin films

In this study Sn doped $$\hbox {In}_{2}\hbox {O}_{3}$$ (ITO) thin films were deposited on glass substrates by e-beam evaporation technique at different oxygen partial pressure and then were annealed in vacuum at $$400\,^\circ \hbox {C}$$ for 1 h. The effects of oxygen partial pressure on the crystallite size, dislocation density, outer cut-off radius of dislocation, fraction of edge and screw dislocation types, the electrical resistivity, optical transmittance, refractive index, porosity and optical band gap energy were studied. The films deposited at an optimized oxygen partial pressure of $$1\times 10^{-4}$$ mbar showed high transparency (88 %) over the visible wavelength region, low electrical resistivity of $$3.2\times 10^{-4}\,\Omega \,\hbox {cm}$$ and the optical band gap of 3.63(3) eV. It is also observed that the best crystal quality (high crystallite size and low dislocation density) are obtained in partial pressure of $$1\times 10^{-4}$$ mbar, indicating the oxygen partial pressure is a key factor in controlling the microstructure, electrical and optical properties of ITO films.

RF magnetron sputtered ITO:Zr thin films for the high efficiency a-Si:H/c-Si heterojunction solar cells

ITO and ITO:Zr films with various thicknesses were prepared on glass substrates by RF magnetron sputtering. We observed a decrease in sheet resistance with increasing film thickness that in good agreement with Fuchs-Sondheimer theory. The ITO films doped with ZrO2 (∼0.2 wt%) showed improvement in some of the electrical and optical properties of ITO films. The surface roughness of ITO:Zr films increased with increasing film thickness. ITO:Zr films with thickness of 120 nm showed highest work function of 5.13 eV, as estimated from XPS data. The ITO:Zr films were employed as front electrodes in HIT solar cells; the best device performance was found to be: Voc = 710 mV, Jsc = 34.44 mA/cm2, FF = 74.8%, η = 18.30% at a thickness of 120 nm. A maximum quantum efficiency (QE) of 89% was recorded for HIT solar cells at a wavelength of 700 nm for 120 nm thick ITO:Zr films.

Effect of growth temperature and coating cycles on structural, electrical, optical properties and stability of ITO films deposited by magnetron sputtering

The effects of growth temperature, coating cycles on the structure, electrical and optical properties of ITO films were investigated, and the stability under high temperature, high temperature & high humidity and alkaline environments was focused. With increasing the growth temperature, the crystalline phase transforms from amorphous to crystalline. The surface morphology shows flat and dense structure. The thickness, sheet resistance and resistivity firstly decrease and then increase, and the optimal sheet resistance and resistivity is 7.6Ω/sq and 1.1×10−4Ωcm. The average visible transmittance of the ITO films and ITO glass exceeds 85% and 80%. The band gap increases from 3.75eV to 3.95eV. The electrical and optical properties of the ITO films are very stable after eight coating cycles. The growth temperature significantly affects the change rate of sheet resistance under high temperature, high temperature & high humidity and alkaline environments. However, the change rate of sheet resistance is stable and sight for eight coating cycles.

Effect of a TiO2Buffer Layer on the Properties of ITO Films Prepared by RF Magnetron Sputtering

Sn-doped In2O3 (ITO) thin films were prepared by radio frequency magnetron sputtering without intentional substrate heating on bare glass and TiO2-deposited glass substrates to investigate the effect of a TiO2 buffer layer on the electrical and optical properties of ITO films. The thicknesses of TiO 2 and ITO films were kept constant at 5 and 100 nm, respectively. As-deposited ITO single layer films show an optical transmittance of 75.9%, while ITO/TiO 2 bi- layered films show a lower transmittance of 76.1%. However, as-deposited ITO/TiO2 films show a lower resistivity (9.87×10 -4 Ωcm) than that of ITO single layer films. In addition, the work function of the ITO film is affected by the TiO 2 buffer layer, with the ITO/TiO2 films having a higher work-function (5.0 eV) than that of the ITO single layer films. The experimental results indicate that a 5-nm-thick TiO2 buffer layer on the ITO/TiO2 films results in better performance than conventional ITO single layer films.

Electron Beam Irradiated ITO Films as Highly Transparent p-Type Electrodes for GaN-Based LEDs

We have investigated the effect of electron beam irradiation on the electrical and optical properties of ITO film prepared by magnetron sputtering method at room temperature. Electron beam irradiation to the ITO films resulted in a significant decrease in sheet resistance from 1.28 x 10(-3) omega cm to 2.55 x 10(-4) omega cm and in a great increase in optical band gap from 3.72 eV to 4.16 eV, followed by improved crystallization and high transparency of 97.1% at a wavelength of 485 nm. The overall change in electrical, optical and structural properties of ITO films is related to annealing effect and energy transfer of electron by electron beam irradiation. We also fabricated GaN-based light-emitting diodes (LEDs) by using the ITO p-type electrode with/without electron beam irradiation. The results show that the LEDs having ITO p-electrode with electron beam irradiation produced higher output power due to the low absorption of light in the p-type electrode.

Effect of reannealing temperature on characteristics of nanocrystalline Sn-doped In2O3thin films for organic photovoltaic cell applications

In this study, nanocrystalline Sn-doped In(2)O(3) (ITO) films were deposited by electron beam evaporation technique and were annealed in air atmosphere from 300°C to 500°C for 30 min. Then, the annealed ITO films in air at 450°C were reannealed in vacuum for 1 h at different temperatures from 300°C to 500°C. The effects of reannealing temperature on structural, electrical, and optical properties of the ITO films were investigated. Increasing reannealing temperature from 300°C to 500°C reduced sheet resistance of ITO thin films from 38 to 12(Ω/sq). The highest transparency over the visible wavelength region of spectrum (95%) was obtained for reannealed films at 450°C. The optimum reannealing temperature for these films is 450°C. Refractive index at 550 nm and porosity for ITO films reannealed at 450°C were 1.92% and 21.2%, respectively. The allowed direct bandgap at different reannealing temperature was evaluated to be in the range of 4.1-4.28 eV. X-ray diffraction results showed that the reannealed films were polycrystalline and a rise in grain size was observed in them. The average grain size in the films reannealed in vacuum at 450°C is about 48.6 nm. Atomic force microscope images indicated that the grain size and root-mean-square roughness films depend on the reannealing temperature. It has been found that reannealing temperature is a key factor in controlling the structural, electrical, and optical properties of ITO films. The power conversion efficiency of the device with ITO films reannealed at 450°C is 1.22% and it is about 58% higher than that of the device without it. This indicates that this film is a promising transparent electrode for organic photovoltaic cells.

진공 열처리에 따른 ITO 박막의 특성 변화

ITO thin films deposited on glass substrate with RF magnetron sputtering were vacuum annealed at 100, 200 and <TEX>$300^{\circ}C$</TEX> for 30 minutes and then effect of annealing temperature on the structural, electrical and optical properties of ITO films were investigated. The structural properties are strongly related to annealing temperature. The annealed films above <TEX>$100^{\circ}C$</TEX> are grown as a hexagonal wurtzite phase and the largest grain size is observed in the films annealed at <TEX>$300^{\circ}C$</TEX>. The electrical resistivity also decreases as low as <TEX>$4.65{\times}10^{-4}{\Omega}cm$</TEX> with a increase in annealing temperature and ITO film annealed at <TEX>$300^{\circ}C$</TEX> shows the lowest sheet resistance of <TEX>$43.6{\Omega}/{\Box}$</TEX>. The optical transmittance in a visible wavelength region also depends on the annealing temperature. The films annealed at <TEX>$300^{\circ}C$</TEX> show higher transmittance of 80.6% than those of the films prepared in this study.

Electrical and Optical Properties of ITO/Au/ITO Multilayer Films for High Performance TCO Films

Effects of a sandwich metallic gold layer on electrical and optical properties of ITO films were investigated in this study. ITO/metal/ITO multilayer films were deposited on borosilicate glass using ultrasonic spray pyrolysis in air atmosphere for the ITO. The metallic layer of Au was coated via a sputtering process in the thickness range of 5–20 nm. The addition of the metallic layer enhanced conductivity, but reduced the transmittance in the multilayer films. ITO/Au/ITO multilayer films have much lower resistivity than ITO single layer film of the same thickness. The ITO/10nm Au/ITO film had the maximum figure of merit or the best performance of these samples.

Investigation of Annealing Effect on the Electrical and Optical Properties of ITO Film Prepared by Sol-Gel Process

Indium tin oxide thin film (ITO film) has been deposited onto the quartz glass by a sol-gel process, followed by annealing in air. The temperature range from 200 to 800 °C and the annealing effect on the optical, electrical and structural properties of ITO films has been studied in detail. ITO Films with a thickness of 100nm had an optical transparency up to 90% in the wavelength range of visible spectrum. The ITO film showed minimum resistivity of 1.65×10-3Ω.cm-1 when annealing temperature was 600°C in air. the rapid annealing process may contribute to the electrical property of ITO film for the densification of the micro structure. but the process may lead to the decrease of transparency for the reflection caused by grain boundary.

Rapid thermal annealing of ITO films

Tin-doped indium oxide (ITO) films with 200 nm thickness were deposited on glass substrates by DC magnetron sputtering at room temperature. And they were annealed by rapid thermal annealing (RTA) method in vacuum ambient at different temperature for 60 s. The effect of annealing temperature on the structural, electrical and optical properties of ITO films was investigated. As the RTA temperature increases, the resistivity of ITO films decreases dramatically, and the transmittance in the visible region increases obviously. The ITO film annealed at 600 °C by RTA in vacuum shows a resistivity of 1.6 × 10 −4 Ω cm and a transmittance of 92%.

Structural, electrical and optical properties of ITO films with a thin TiO 2 seed layer prepared by RF magnetron sputtering

Tin-doped indium oxide (ITO) films were deposited by RF magnetron sputtering on TiO 2-coated glass substrates (the TiO 2 layer is usually called seed layer). The properties of ITO films prepared at a substrate temperature of 300 °C on bare and TiO 2-coated glass substrates have been analyzed by using X-ray diffraction, atomic force microscope, optical and electrical measurements. Comparing with single layer ITO film, the ITO film with a TiO 2 seed layer of 2 nm has a remarkable 41.2% decrease in resistivity and similar optical transmittance. The glass/TiO 2 (2 nm)/ITO film achieved shows a resistivity of 3.37 × 10 −4 Ω cm and an average transmittance of 93.1% in the visible range. The glass/TiO 2 may be a better substrate compared with bare glass for depositing high quality ITO films.

The correlation between preferred orientation and performance of ITO thin films

The tin-doped indium oxide (ITO) thin films were prepared by reactive thermal evaporation on the glass substrates. The effects of substrate temperatures (T-s) on the grain preferred orientation, the electrical and optical properties of ITO films were studied. X-ray diffraction (XRD) patterns indicated that the preferred orientation of film changes from (222) to (400) as T, > 200 degrees C. It can be explained by that the low-index crystallographic planes are easier to be formed when the adatoms have high surface mobility. The Hall measurements indicated that both the concentration and mobility of carrier increase with increasing T,,,. The grain orientation of film does not influence the transmissivity and the carrier concentration, but enhances the carrier mobility. The transmissivity of ITO films is over 90% in the visible wavelength region (except that of the film deposited at 125 degrees C). A minimum resistivity of 5 X 10-4 Omega cm is achieved for the (400) preferred orientation film. Thus, the highest figure of merit of 3.5 x 10(-2) square/Omega is obtained for the film with (400) preferred orientation. The correlation between the preferred orientation and electrical and optical properties are discussed.

Structural, optical and electrical peculiarities of r.f. plasma sputtered indium tin oxide films

In this work the influence of the deposition conditions on the structural, electrical and optical properties of the ITO films was studied. Films were deposited by r.f. plasma sputtering technique in Ar and varying Ar + O 2 gas mixtures, with and without substrate heating. Transmittance and reflectance of the films were measured in the range 350–2500 nm; the refractive index ( n) and the extinction coefficient ( k) were calculated by the spectral data simulation. The sheet resistance of the films was measured by four-point probe method. X-ray diffraction analysis was performed to study the texture of the films. Threshold behaviour was observed in the optical and electrical properties of ITO films deposited in Ar + O 2 atmosphere at a certain oxygen concentration determined by a fix combination of all other deposition conditions. A schematic diagram for the change of the film properties versus composition was suggested, which explains the obtained results.

The role of oxygen and hydrogen partial pressures on structural and optical properties of ITO films deposited by reactive rf-magnetron sputtering

Sn doped In 2O 3 films are deposited by rf-magnetron sputtering at 300 °C under Ar, Ar + O 2 and Ar + H 2 gas ambients. For the film prepared under argon ambient, electrical resistivity 6.5 × 10 −4 Ω cm and 95% optical transmission in the visible region have been achieved optimizing the power and chamber pressure during the film deposition. X-ray diffraction spectra of the ITO film reveal (2 2 2) and (4 0 0) crystallographic planes of In 2O 3. With the introduction of 1.33% oxygen in argon, (2 2 2) peak of In 2O 3 decreases and resistivity increases for the deposited film. With further increase of oxygen in the sputtering gas mixture crystallinity in the film deteriorates and both the peaks disappeared. On the other hand, when 1.33% hydrogen is mixed with argon, the resistivity of the deposited film decreases to 5.5 × 10 −4 Ω cm and the crystallinity remains almost unchanged. In case of reactive sputtering, the deposition rate is lower compared to that in case of non-reactive sputtering. HRTEM and first Fourier patterns show the highly crystalline structure of the samples deposited under Ar and Ar + H 2 ambients. Crystallinity of the film becomes lower with the introduction of oxygen in argon but refractive index increases from 1.86 to 1.9. The surface morphology of the ITO films have been studied by high resolution scanning electron microscopy.

Influence of Metal Impurity Defects on the Electrical and Optical Properties of ITO Films on the PEN Substrates

AbstractIndium tin oxide (ITO) has drawn a great deal of attention due to its potential use as transparent electrodes in organic light emitting diode (OLED) and photovoltaic applications. This work focuses on understanding the role of impurity defects on the electrical conduction and transmittance of ITO. Thin films of ITO with high carrier concentration have been deposited onto polyethylene napthalate (PEN) substrates by electron-beam deposition without introduction of oxygen into the chamber. The influence of air anneals on the electrical and optical properties of ITO/PEN samples can is evaluated in terms of the oxygen content and is explained in terms of changes in the free electron concentrations. Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy analysis were used to determine the oxygen content in the film. A Hall effect measurement is used to determine the dependence of electrical properties on oxygen content. The electrical properties of the ITO films such as carrier concentration, electrical mobility, and resistivity abruptly changes after annealing in the air atmospheres. In addition, optical transmittance is improved from 7 to 71 % and optical band gap changes from 3.18 to 3.25 eV after heat treatment. The optical band gap narrowing behavior is because of impurity band and heavy carrier concentration. Metal impurity clusters form in the films as a result of oxygen deficiency and also generate defects and/or impurity states in the band gap and produces an optical band gap shift by merging of these impurity states and conduction band.