Properties Of Indium Tin Oxide Films Research Articles

Influence of different plasma treatments on electrical and optical properties on sputtered AZO and ITO films

In this paper, the influence of hydrogen and argon plasma treatment on the electro-optical and structural properties of aluminum-doped zinc oxide (AZO) and indium tin oxide (ITO) films were studied. The films were exposed for different times and at various plasma powers. AZO films did not reduce for all plasma conditions, while ITO films were deteriorated when exposed to hydrogen plasma for even a short treatment time. The argon plasma has little effect on the properties of AZO and ITO films. When the ITO films were exposed to Ar plasma for a long time, however, the optical properties of ITO films were strongly influenced.

Influence of O2 Flux on Compositions and Properties of ITO Films Deposited at Room Temperature by Direct-Current Pulse Magnetron Sputtering

Indium tin oxide (ITO) films were deposited on glass substrates at room temperature by dc pulse magnetron sputtering. Varying O2 flux, ITO films with different properties are obtained. Both x-ray diffractometer and x-ray photoelectron spectrometer are used to study the change of crystalline structures and bonding structures of ITO films, respectively. Electrical properties are measured by four-point probe measurements. The results indicate that the chemical structures and compositions of ITO films strongly depend on the O2 flux. With increasing O2 flux, ITO films display better crystallization, which could decrease the resistivity of films. On the contrary, ITO films contain less O vacancies with increasing O2 flux, which could worsen the conductive properties of films. Without any heat treatment onto the samples, the resistivity of the ITO film could reach 6.0 × 10−4 Ω ·cm, with the optimal deposition parameter of 0.2 sccm O2 flux.

Study of ITO Thin Film Deposited by RF Magnetron Sputter at Low Temperature

ITO thin films used in PTCDA/Si detector should be made at low temperature for low temperature resistance of substrate. ITO thin films were deposited at low temperature by RF magnetron sputtering. Properties of ITO thin films such as conductivity and transmission measured by 4 point probe and UV spectral photometry respectively. The results show that the sputtering pressure is an important parameter in the deposition of indium tin oxide（ITO） thin films, which affects the properties of ITO films. The optimized parameter for preparation of ITO thin films at low temperature are sputtering pressure 0.45 Pa, sputtering power 45W. Meanwhile, the post-annealing is not necessary.

Effects of Substrate Temperature and Vacuum Annealing on Properties of ITO Films Prepared by Radio-Frquency Magnetron Sputtering

Indium tin oxide (ITO) films were prepared by rf magnetron sputtering under two conditions: (i) at substrate temperature Ts from room temperature (RT) to 350° C, (ii) with additional post-annealing in vacuum at 400° C for 30 min in comparison of their crystalline structures, and electrical-optical properties of the films deposited. From the experimental results, it is found that, under the first condition, the crystalline structures and the electrical-optical properties of the films are improved with the increasing Ts. Under the other condition, i.e. with the additional post-annealing, the films exhibit higher degree of crystallinities and better electrical-optical properties. Under the two deposition conditions, inter-relation between electrical-optical properties and the crystalline structure is observed clearly. However, even under the same annealing condition, it is observed that improved properties of the films are different, depending on their deposition temperatures, which implies that an initial stage of the ITO film before annealing is an important factor for the film's properties improved after annealing. The resistivity of 2.33 × 10−4 Ω·cm can be achieved at Ts of 350° C after annealing.

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.

Piezoresistive response of ITO films deposited at room temperature by magnetron sputtering

Indium tin oxide (ITO) thin films have been deposited on (100) Si substrates by RF magnetron sput- tering from a compact target (90% In2O3-10% SnO2 in weight) with 6 in. in diameter. In order to perform elec- tromechanical characterizations of these films, strain gau- ges were fabricated. An experimental set-up based on bending beam theory was developed to determine the longitudinal piezoresistive coefficient (pl) of the strain gauges fabricated. It has been confirmed that electrical resistance of the strain gauges decreases with load increa- ses which results a negative gauge factor. A model based on the activation energy was used to explain the origin of this negative signal. The influence of the temperature on piezoresistive properties of ITO films was also evaluated.

Effect of surfactants on the structure and photoelectric properties of ITO films by sol-gel method

The Indium tin oxide (ITO) thin film possesses excellent photoelectric properties that enable it to act as an ideal transparent conductor. To obtain high-quality ITO films through sol-gel method, the ionic surfactant monoethanolamine and the non-ionic surfactant polyethylene glycol (PEG) were added to the ITO precursor slurry. The influences of surfactants on the structural and photoelectric properties of ITO film samples were investigated. XRD patterns indicated that surfactant monoethanolamine contributed to film predominant grain orientation along the (400) plane. The high transmittance (over 95%) was attributed to the preferred orientation and the grain size expansion of ITO films. SEM showed that the surface particle size and the morphology of ITO films were strongly dependent on the kind of surfactants used. Moving to the shortwave region, the absorption edge of the films exhibited the Burstein-Moss shift.

INFLUENCE OF CONTINUOUS AND DISCONTINUOUS DEPOSITIONS ON PROPERTIES OF ITO FILMS PREPARED BY DC MAGNETRON SPUTTERING

Indium tin oxide (ITO) films were deposited on glass substrate without external heating by DC magnetron sputtering with continuous deposition of 800 s (S1) and discontinuous depositions of 400 s × 2 times (S2), 200 s × 4 times (S3) and 100 s × 8 times (S4). The structural, surface morphology, optical transmittance and electrical resistivity of ITO films were measured by X-ray diffraction, atomic force microscope, spectrophotometer and four-point probe, respectively. The deposition process of the S1 condition shows the highest target voltage due to more target poisoning occurrence. The substrate temperature of the S1 condition increases with the saturation curve of the RC charging circuit while other conditions increase and decrease due to deposition steps as DC power turns on and off. Target voltage and substrate temperature of ITO films decrease when changing the deposition conditions from S1 to S2, S3 and S4, respectively. The preferential orientation of ITO films were changed from dominate (222) plane to (400) plane with the increasing number of deposition steps. The ITO film for the S4 condition shows the lowest electrical resistivity of 1.44 × 10-3 Ω· cm with the highest energy gap of 4.09 eV and the highest surface roughness of 3.43 nm. These results were discussed from the point of different oxygen occurring on the surface ITO target between the sputtering processes which affected the properties of ITO films.

신경회로망을 이용한 ITO 박막 성장 공정의 모형화

Compare to conventional Indium Tin Oxide (ITO) film deposition methods, cesium assisted sputtering method has been shown superior electrical, mechanical, and optical film properties. However, it is not easy to use cesium assisted sputtering method since ITO film properties are very sensitive to Cesium assisted equipment condition but their mechanism is not yet clearly defined physically or mathematically. Therefore, to optimize deposited ITO film characteristics, development of accurate and reliable process model is essential. For this, in this work, we developed ITO film deposition process model using neural networks and design of experiment (DOE). Developed model prediction results are compared with conventional statistical regression model and developed neural process model has been shown superior prediction results on modeling of ITO film thickness, sheet resistance, and transmittance characteristics.

The characteristics of indium tin oxide films prepared on various buffer layer-coated polymer substrates

The optoelectronic and mechanical properties of flexible indium tin oxide (ITO) films are critical to the development of flexible optoelectronic devices. To improve the characteristics of the flexible films, the effects of inorganic buffer layers on the optoelectronic and mechanical characteristics of flexible ITO films prepared by ion-beam assisted deposition at room temperature were investigated. The results show that four inorganic buffer materials: SiO 2, Ta 2O 5, Al 2O 3 and TiO 2, have different effects on the optical transmission, sheet resistance and mechanical properties of ITO films. Ta 2O 5 buffer layer induces the highest optical transmission. SiO 2 buffer layer leads to the lowest sheet resistance. TiO 2 buffer layer reveals the most superior electrical stability against bending, which is attributed to the low thermal stress in ITO film.

Structural Properties of Post Annealed ITO Thin Films at Different Temperatures

Indium tin oxide (ITO) thin films were deposited on glass substrates by RF sputtering using an ITO ceramic target (In2O3-SnO2, 90-10 wt. %). After deposition, samples were annealed at different temperatures in vacuum furnace. The post vacuum annealing effects on the structural, optical and electrical properties of ITO films were investigated. Polycrystalline ITO films have been analyzed in wide optical spectrum, X-ray diffraction and four point probe methods. The results show that increasing the annealing temperature improves the crystallinity of the films. The resistivity of the deposited films is about 19×10 -4 Ωcm and falls down to 7.3×10 -5 Ωcm as the annealing temperature is increased to 500 °C in vacuum.

Properties of indium tin oxide films deposited on unheated polymer substrates by ion beam assisted deposition

The optical, electrical and mechanical properties of indium tin oxide (ITO) films prepared on polyethylene terephthalate (PET) substrates by ion beam assisted deposition at room temperature were investigated. The properties of ITO films can be improved by introducing a buffer layer of silicon dioxide (SiO 2) between the ITO film and the PET substrate. ITO films deposited on SiO 2-coated PET have better crystallinity, lower electrical resistivity, and improved resistance stability under bending than those deposited on bare PET. The average transmittance and the resistivity of ITO films deposited on SiO 2-coated PET are 85% and 0.90 × 10 − 3 Ω cm, respectively, and when the films are bent, the resistance remains almost constant until a bending radius of 1 cm and it increases slowly under a given bending radius with an increase of the bending cycles. The improved resistance stability of ITO films deposited on SiO 2-coated PET is mainly attributed to the perfect adhesion of ITO films induced by the SiO 2 buffer layer.

Correlation between diffraction patterns and surface morphology to the model of oxygen diffusion into ITO films

Indium tin oxide (ITO) films post-annealed in air usually have higher resistivity compared to the ITO films post-annealed in vacuum. This is likely due to the incorporation of oxygen atoms into the ITO films during post-annealing treatment in air. In this paper, we studied mainly the electrical properties of ITO films as a function of post-annealing temperature and post-annealing ambient. Our results show that the ITO films post-annealed in vacuum have lower resistivity compared to the ITO films post-annealed in air. From the results, we relate the model of oxygen diffusion with the AFM images and the (4 0 0)/(2 2 2) XRD peak ratio. We observe that the ITO films post-annealed in vacuum have larger grain size through the AFM images. The reduction of grain boundary scattering leads to higher conductivity. Furthermore, the ITO films post-annealed in vacuum have rather constant (4 0 0)/(2 2 2) XRD peak ratio. This result indicates that there is less oxygen atoms diffuse into the ITO films in vacuum. The ITO film post-annealed at 500 °C in vacuum has a grain size of ∼125 nm and resistivity of ∼3.49 × 10 −4 Ω cm.

Fabrication and opto-electric properties of ITO/ZnO bilayer films on polyethersulfone substrates by ion beam-assisted evaporation

Transparent conducting oxides bilayer films stacked by one 130-nm-thick indium tin oxide (ITO) top layer and one 75-nm-thick zinc oxide (ZnO) buffer layer were grown onto polyethersulfone (PES) substrates by ion beam-assisted evaporation. The effects of ion energy and ZnO buffer layers on the structural and opto-electric properties of ITO films were initially investigated. The as-deposited ZnO buffer layers show wurtzite (0 0 2) preferred orientation on the PES substrates with ion beam assistance. The results of X-ray diffraction reveal a marked increase in the crystallinity of the ITO films which use ZnO as a buffer layer material. A drop of ∼60% in electrical resistivity of the ITO film on the PES can be achieved by using ZnO buffer layer. The transmittance of the ITO/ZnO bilayer was not deteriorated due to the insertion of ZnO layer. The lowest electrical resistivity of 6.552×10 −4 Ω-cm associated with the transmittance of ∼80% at the wavelength of 550 nm can be obtained for the ITO film on the ZnO-coated PES at ion energy of 60 eV. The ITO films on the ZnO-buffered PES with moderate control of ion energy have a promising future for the application of the contact layers for flexible solar cells.

Preparation of indium tin oxide thin films without external heating for application in solar cells

Indium tin oxide (ITO) films were grown without external heating in an ambient of pure argon by RF-magnetron sputtering method. The influence of argon ambient pressure on the electro-optical properties of as-deposited ITO films was investigated. The morphology, structural and optical properties of ITO films were examined and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and UV–VIS transmission spectroscopy. The deposited ITO films with a thickness of 300 nm show a high transparency between 80% and 90% in the visible spectrum and 14–120 Ω/□ sheet resistance under different conditions. The ITO films deposited in the optimum argon ambient pressure were used as transparent electrical contacts for thin film Cu(In,Ga)Se2 (CIGS) solar cells. CIGS solar cells with efficiencies of the order of 7.0% were produced without antireflective films. The results have demonstrated that the developed ITO deposition technology has potential applications in thin film solar cells.

Influence of Structural and Electrical Properties of ITO Films on Electrochromic Properties of WO<sub>3</sub> Films

Indium tin oxide (ITO) films had been deposited on glass substrate without substrate heating and then tungsten oxide (WO3) films were deposited on ITO films by DC magnetron sputtering. In this work, we present the annealing ambient effect of ITO substrate on electrochromic properties of WO3 films. The ITO films were annealing in air and in vacuum at 350°C before coating with WO3 films. The structural, optical, and electrical properties of ITO films for as-deposited, annealing in air and in vacuum were investigated by X-ray diffraction, UV-VIS-NIR spectroscope and four point probe. The ITO films had a better crystallinity and lager grain size after annealing in air and in vacuum. The resistivity of ITO films increase with annealing in air, but decrease with annealing in vacuum. The WO3 films show difference surface morphology with higher grain size and surface roughness when coating on annealed ITO films in both cases. The electrochemical properties of film systems were characterized by cyclic voltammetry. The film systems of ITO plus WO3 showed that the charge capacity of ITO substrate annealing in vacuum was higher than the as-deposited ITO substrate and the ITO substrate annealing in air, respectively. This result corresponded to electrical conductivity of each ITO substrate.

Effect of annealing on the structural, optical and electrical properties of ITO films by RF sputtering under low vacuum level

Indium tin oxide (ITO) thin films were prepared by RF sputtering of ceramic ITO target in pure argon atmosphere at a high base pressure of 3×10 −4 mbar without substrate heating and oxygen admittance. The use of pure argon during deposition resulted in films with high transparency (80–85%) in the visible and IR wavelength region. The films were subsequently annealed in air in the temperature range 100–400 °C. The annealed films show decreased transmittance in the IR region and decreased resistivity. The films were characterized by electron microscopy, spectrophotometry and XRD. The predominant orientation of the films is (2 2 2) instead of (4 0 0). The transmission and reflection spectra in the wavelength range 300–2500 nm are used to study the optical behaviour of the films. The optical transmittance and reflectance spectra of the films were simultaneously simulated with different dielectric function models. The best fit of the spectrophotometric data was obtained using the frequency-dependent damping constant in the Drude model coupled with the Bruggeman effective medium theory for the surface roughness. It has been found that the sputtering power and the chamber residual pressure play a key role in the resulting optical properties. This paper presents the refractive index profile, the structure determined from the XRD and the electrical properties of ITO films. It has been found from the electrical measurement that films sputtered at 200 W power and subsequently annealed at 400 °C have a sheet resistance of 80 Ω/□ and resistivity of 1.9×10 −3 Ωcm.

OLED용 ITO박막의 공정조건과 품질특성 추론에 근거한 품질관리

Recently, research on a flat panel display(FPD) has focused on organic light-emitting display(OLED) which has wide angle of view, high contrast ratio and low power consumption. ITO(Indium-Tin-Oxide) films are the most widely used material as a transparent electrode of OLED and also in many other display devices like LCD or PDP. The performance and efficiency of OLED is related to the surface condition of ITO coated glass substrate. The typical surface defect of glass substrate is measured for electric characteristics and physical condition for transmittance and roughness. Since ITO coated glass substrate can be destroyed for inspection about surface roughness, sheet resistance, film thickness and transmittance, precise fabrication condition should be made based on the estimated relationship. In this paper, ITO films were prepared on the commercial glass substrate by the Ion-Plating method changing the partial pressure of gas(Ar, 02) and the chamber temperature between <TEX>$200^{\circ}C$</TEX> and <TEX>$300^{\circ}C$</TEX>. The characteristics of films were examined by the 4-point probe, supersonic thickness measurement, transmittance measurement and AFM. We estimated the relationship between processing parameters(Ar gas, O2 gas, Temperature) and properties of ITO films (Sheet Resistance, Film Thickness, Transmittance, Surface Roughness).

Characterization of ITO/CdO/glass thin films evaporated by electron beam technique

A thin buffer layer of cadmium oxide (CdO) was used to enhance the optical and electrical properties of indium tin oxide (ITO) films prepared by an electron-beam evaporation technique. The effects of the thickness and heat treatment of the CdO layer on the structural, optical and electrical properties of ITO films were carried out. It was found that the CdO layer with a thickness of 25 nm results in an optimum transmittance of 70% in the visible region and an optimum resistivity of 5.1×10−3 Ω cm at room temperature. The effect of heat treatment on the CdO buffer layer with a thickness of 25 nm was considered to improve the optoelectronic properties of the formed ITO films. With increasing annealing temperature, the crystallinity of ITO films seemed to improve, enhancing some physical properties, such as film transmittance and conductivity. ITO films deposited onto a CdO buffer layer heated at 450 °C showed a maximum transmittance of 91% in the visible and near-infrared regions of the spectrum associated with the highest optical energy gap of 3.61 eV and electrical resistivity of 4.45×10−4 Ω cm at room temperature. Other optical parameters, such as refractive index, extinction coefficient, dielectric constant, dispersion energy, single effective oscillator energy, packing density and free carrier concentration, were also studied.

Effects of heat treatment on morphological, optical and electrical properties of ITO films by sol-gel technique

Indium-tin-oxide(ITO) films were prepared on the quarts glass by sol-gel technique. Effects of different heat treatment temperatures and cooling methods on the morphological, optical and electrical properties of ITO films were measured by TG/DTA, IR, XRD, SEM, UV-VIS spectrometer and four-probe apparatus. It is found that the crystallized ITO films exhibit a polycrystalline cubic bixbyite structure. The heat treatment process has significant effects on the morphological, optical and electrical properties of ITO films. Elevating the heat treatment temperature can perfect the crystallization process of ITO films, therefore the optical and electrical properties of ITO films are improved. But the further increasing of heat treatment temperature results in the increment of ITO films' resistivity. Compared with ITO films elaborated by furnace cooling, those prepared through air cooling have following characteristics as obviously decreased crystalline size, deeply declined porosity, more compact micro-morphology, improved electrical property and slightly decreased optical transmission.