• Structural Engineering and Mechanics
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• v.74 no.2
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• pp.215-225
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• 2020

Thin films easily wrinkle under compressive loading due to their small bending stiffness resulting from their tiny thickness. For a thin film deposited on a functionally graded substrate with non-uniform stiffness exponentially changes along the length span in this paper, the uniaxial wrinkling problem is solved analytically in terms of hyper-Bessel functions. For infinite, semi-infinite and finite length systems the wrinkling load and wrinkling wavenumber are determined and compared with those in literature. In comparison with a homogeneous substrate-bounded film in which the wrinkling pattern is uniform along the length span, for a functionally graded substrate-film system the wrinkles accumulate around the softer location of the functionally graded substrate. Therefore, the effective length of the film influenced by the wrinkles decreases, the amplitude of the wrinkles on softer regions of the functionally graded substrate grows and the wrinkling load of the functionally graded substrates with higher softening rate decreases more. The results of the current research are expected to be useful in science and technology of thin films and wrinkling of the structures especially living tissues.

• Transactions on Electrical and Electronic Materials
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• v.8 no.6
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• pp.274-277
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• 2007

In this study, liquid crystal(LC) aligning capabilities for homeotropic alignment on the $SiO_x$ thin film by electron beam evaporation method were investigated. Also, the control of pretilt angles and thermal stabilities of the nematic liquid crystal(NLC) treated on $SiO_x$ thin film were investigated. A high pretilt angle of about $86.5^{\circ}$ was obtained, and also the suitable pretilt angle of the NLC on the $SiO_x$ thin film at $10{\sim}50nm$ thickness with e-beam evaporation can be achieved. The uniform LC alignment and good thermal stabilities on the $SiO_x$ thin film surfaces with electron beam evaporation can be achieved. It is considered that the LC alignment on the $SiO_x$ thin film by electron beam evaporation is attributed to elastic interaction between LC molecules and micro-grooves at the $SiO_x$ thin film surface created by evaporation.

• Journal of the Semiconductor & Display Technology
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• v.14 no.3
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• pp.33-36
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• 2015

It has increased several decades in the field of Indium Tin Oxide (ITO) transparent thin film, However, a major problem with this ITO thin film application is high cost compared with other transparent thin film materials[1]. So far, in order to overcome this disadvantage, we show that a transparent ITO/Ag/i-ZnO multilayer thin film electrode would be more cost-effective and it has not only highly transparent but also conductive properties. The aim of this research has therefore been to try and establish how ITO/Ag/i-ZnO multilayer thin film would be more effective than ITO thin film. Herein, we report the properties of ITO/Ag/i-ZnO multilayer thin film by using optical spectroscopic method and measuring sheet resistance. At a certain total thickness of thin film, sheet resistance of ITO/Ag/i-ZnO multilayer was drastically decreased than ITO layer approximately $40{\Omega}/{\Box}$ at same visible light transmittance. (minimal point $5.2{\Omega}/{\Box}$). Tendency, which shows lowly sheet resistive in a certain transmittance, has been observed, hence, it should be suitable for transparent electrode device.

• Korean Journal of Materials Research
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• v.25 no.1
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• pp.54-59
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• 2015

Glancing angle deposition (GLAD) is a powerful technique to control the morphology and microstructure of thin film prepared by physical vapor deposition. Chromium (Cr) thin films were deposited on a polymer substrate by a sputtering technique using GLAD. The change in thickness and Vickers microhardness for the samples was observed with a change in the glancing angle. The adhesion properties of the critical load (Lc) by a scratch tester for the samples were also measured with varying the glancing angle. The critical load, thickness and Vickers microhardness for the samples decreased with an increase in the glancing angle. However, the thickness of the Cr thin film prepared at a $90^{\circ}$ glancing angle showed a relatively large value of 50 % compared to that of the sample prepared at $0^{\circ}$. The results of X-ray diffraction and scanning electron microscopy demonstrated that the effect of GLAD on the microstructure of samples prepared by sputter technique was not as remarkable as the samples prepared by evaporation technique. The relatively small change in thickness and microstructure of the Cr thin film is due to the superior step-coverage properties of the sputter technique.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.215-219
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• 2007

In this work, the indium zinc oxide (IZO) films had been deposited on the glass substrate coated with the SiO film. Based on a comparative investigation of the IZO monolayer and IZO/SiO multilayer, it is shown that the thickness of SiO film has a great effect on the mechanical properties of the thin films. The AFM images of the IZO thin film included the SiO film were shown smoother surfaces than monolayer. Resistivity was in inverse proportion to Mobility. If it deposited the SiO film on the substrate, the layer of change was generated between two layer(SiO and substrate). The layer of change influenced resistance because of oxygen content was more than the IZO monolayer.

• Korean Journal of Materials Research
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• v.10 no.4
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• pp.264-269
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• 2000

TiO$_2$thin films were prepared on the glass by a conventional spin coating method with $TiO_2$ sol(30wt%, anatase). The thickness of the thin films were controlled by the number of coating cycles: one cycle is composed of spin coating, drying, and heating process. The reaction rate of the film was obtained by the photodecomposition of gaseous benzene under 0.44 and 2.0mW/$\textrm{cm}^2$ UV light on the film surface. For an incident UV light intensity of 0.44mW/$\textrm{cm}^2$, the reaction rate was increased with the thickness of the film, caused by extent of surface area, but there was no change over the thickness of about 4$\mu\textrm{m}$. The porous $TiO_2$ thin film has comparatively vast effective surface area, which under relatively high-intensity UV illumination causes the reaction rate to be controlled by the film thickness.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.4
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• pp.199-203
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• 2017

$ZrO_2/PSS$ thin film with a high refractive index was fabricated on a glass substrate by a layer-by-layer self-assembly method. The surface morphology and thickness of the fabricated $ZrO_2/PSS$ thin films were measured as a function of the number of $(ZrO_2/PSS)n$. As the number of $(ZrO_2/PSS)n$ increased from n = 5 to n = 20, RMS roughness decreased from 29.01 nm to 8.368 nm. The $ZrO_2$ thin films exhibited high transmittance of 85% or more; and the 15-bilayer thin film exhibited the highest transmittance among the samples. The transmittance of the fabricated $(ZrO_2/PSS)_{15}$ thin film was ca. 90.8% in the visible range. The refractive index of the glass substrate coated by a $(ZrO_2/PSS)_{15}$ thin film with a thickness of 160 nm increased from ca. 1.52 to 1.74 at the 632 nm wavelength.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.6
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• pp.577-582
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• 2003

This paper describes a new technique for thickness measurement of a very thin layer less than one-quarter of the wavelength of ultrasonic wave used in the ultrasonic pulse-echo measurements. The technique determines the thickness of a thin layer in a tapered medium from constructive interference of multiple reflection waves. The interference characteristics are derived and investigated in theoretical and experimental approaches. Modified total reflection wave g(t) defined as difference between total and first reflection waves increases in amplitude as the interfacial layer thickness decreases down to zero. A layer thickness less than one-tenth of the ultrasonic wavelength is measured using the maximum amplitude of g(t) with a good accuracy and sensitivity. The method also requires no inversion process to extract the thickness information from the waveforms of reflected waves, so that it makes possible to have the on-line thickness measurement of a thin layer such as a lubricating oil film in thrust bearings and journal bearings during manufacturing process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.979-982
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• 2004

The ZnO thin films were prepared by the FTS (facing target sputtering) system, which enables to provide high density plasma and a high deposition rate at a low working gas pressure. We introduced the AZO thin film in order to improve the crystallographic properties of ZnO thin film because of the AZO(ZnO:Al) thin film has an equal crystal structure to the ZnO thin film. ZnO/AZO thin films were deposited at a different oxygen gas flow ratio, R.T. 2mTorr working pressure and a 0.8A sputtering current. The film thickness and c-axis preferred orientation of ZnO/AZO/glass thin films were measured by ${\alpha}$-step and an x-ray diffraction (XRD) instrument. In the results, we could prepare the ZnO thin film with c-axis preferred orientation of about 6$^{\circ}$ on substrate temperature R.T. at O$_2$ gas flo rate 0.5.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.215-218
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• 2011

A novel design of gas sensor using Ga-doped ZnO (GZO) thin films which are deposited on low temperature co-fired ceramic (LTCC) substrates is presented. The LTCC substrates with thickness of 400 ${\mu}m$ are fabricated by laminating 12 green tapes which consist of alumina and glass particle in an organic binder. The GZO thin films with different thickness are deposited on LTCC substrates, by RF magnetron sputtering method. The microstructure and sensing properties of GZO gas sensing films are analyzed as a function of the film thickness. The films are well crystallized in the hexagonal (wurzite) structure with increasing thickness. The maximum sensitivity of 3.49 is obtained at 100 nm film thickness and the fastest 90% response time of 27.2 sec is obtained at 50 nm film thickness for the operating temperature of $400^{\circ}C$ to the $NO_2$ gas.