• Journal of the Korean institute of surface engineering
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• v.42 no.3
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• pp.128-132
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• 2009

Transparent conducting thin films of indium tin oxide(ITO) co-sputtered with aluminum-doped zinc oxide(AZO) were deposited on glass substrate by dual magnetron sputtering. It was found that the electrical properties and structural characteristics of the films are significantly changed according to the sputtering power of the AZO target. The IAZTO film prepared with D.C power of ITO at 100 W and R.F power of AZO at 50 W shows an electrical resistivity of $4.6{\times}10^{-4}{\Omega}{\cdot}cm$ and a sheet resistance of $30{\Omega}/{\square}$ (for 150 nm thick). Besides of the improvement of the electrical properties, compared to the ITO films deposited at the same process conditions, the IAZTO films have very smooth surface, which is due to the amorphous nature of the films. However, the electrical conductivity of the IAZTO films was found to be deteriorated along with the crystallization in case of the high temperature deposition (above $310^{\circ}C$). In this work, high quality amorphous transparent conductive oxide layers could be obtained by mixing AZO with ITO, indicating possible use of IAZTO films as the transparent electrodes in OLED and flexible display devices.

• Journal of the Optical Society of Korea
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• v.14 no.3
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• pp.260-265
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• 2010

This paper proposes a transflective configuration of the dual operating mode liquid crystal display, which has transmissive dynamic and reflective memory parts in its pixel. By employing a wideband structure and optimizing the cell-gap of the liquid crystal layer, the reflective memory part shows a very low reflectance in the dark state, good dispersion properties for the entire visible range, as well as high reflectance in the bright state. The transmissive dynamic part is designed to have the same cell-gap and rubbing direction as those of the reflective part. The driving voltage of the dynamic part and transmittance of the bright state can also be controlled by using compensation film with a positive a-plate, which can compensate the reflective part. Experimental results in the memory part operation demonstrate that the contrast ratio is over 50:1 and the reflectance in the dark state is reduced to 56% on average of that of the conventional dual mode configuration for the entire visible range. The contrast ratio of the dynamic part is 300:1.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.103-107
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• 2023

To solve the reliability problem of organic devices that are often used outdoors, multifunctional gas barriers that block reactive gases such as moisture and oxygen and reflect harmful light such as ultraviolet rays are needed. In this study, ALD nanolaminate-based optically functional n-DBR was developed to overcome the poor gas permeability of polymer substrates and protect organic devices from harmful light. n-DBR not only achieved a WVTR of 8.76 × 10^-6 g·m^-2·day^-1, but also showed a visible light transmittance of 94.3% and an ultraviolet ray blocking ability of 2.67%. In particular, n-DBR based on a nanolaminate structure maintained its permeability characteristics even in a high temperature and high humidity environment despite being used as a layer of Al₂O₃. This functional barrier Structure can not only be used as a functional encapsulation barrier for the reliability of organic devices, but can also be used as a tinting film for vehicles.

• Journal of the Korean Vacuum Society
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• v.17 no.1
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• pp.73-79
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• 2008

In order to apply for transparent conductive oxide(TCO), we deposited ZnO thin films on the glass at room temperature by RF magnetron sputtering method. Deposition conditions for high transmittance and low resistivity were optimized in our previous studies. Under the deposition condition with the RF power of 200 W, target to substrate distance of 30 mm and working pressure of 5 mTorr, highly conductive($7.4{\times}10^{-3}{\Omega}cm$) and transparent(over 85%) ZnO films were prepared. Highly oriented ZnO film in the [002] direction were obtained with specifically designed ZnO targets. Systematic study on dependence of deposition parameters on electrical and optical properties of the as-grown ZnO films were mainly investigated in this work. And for application tests using these films as transparent conductive oxide anodes, wet chemical etching behaviors of ZnO films were also investigated using various chemicals. Wet-chemical etching behavior of ZnO films were investigated using various acid solutions. The concentrations of these different acid solutions were controlled to study the etching shapes and etching rate. ZnO films were anisotropically etched at various concentrations and wet etching led to crater-like surface structure. Also we firstly found that the etching rate and etching shapes of ZnO films strongly depended on the etchant concentrations (i.e. pH) and the etching rate is exponentially decreased with increasing pH values regardless of the acid etchants.

• Korean Journal of Optics and Photonics
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• v.16 no.2
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• pp.168-173
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• 2005

Ag-doped $TiO_2$ thin films were prepared by RF magnetron co-sputtering method, and their physical and chemical properties were examined as a function of calcination temperature. XRD results showed that the crystallite size of Ag-doped films was smaller than that of the $TiO_2$ thin films. SEM results showed that the particle size of $Ag/TiO_2$ film was smaller and more uniform than pure $TiO_2$ film. The films had high transparency in the visible range. The films calcined at $600^{\circ}C$ were the anatase phase, and the films calcined at $900^{\circ}C$ were a mixture of anatase and rutile phases. The absorption edge of films calcined at $900^{\circ}C$ was red-shifted. This is due to the augmented absorption resulting from the phase transformation from anatase to rutile phase. And the transmittance of films decreased by the light scattering and absorption in the films. Photocatalytic activity of $Ag/TiO_2$ thin films was higher than that of the pure $TiO_2$ thin films.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.4
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• pp.665-670
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• 2020

Buffer layer in CIGS thin-film solar cells improves energy conversion efficiency through band alignment between the absorption layer and the window layer. ZnS is a non-toxic II-VI compound semiconductor with direct-transition band gaps and n-conductivity as well as with excellent lattice matching for CIGS absorbent layers. In this study, the structural and optical properties of ZnS thin films, deposited by RF magnetron sputtering method and subsequently performed by the rapid thermal annealing treatment, were investigated for the buffer layer. The zincblende cubic structures along (111), (220), and (311) were shown in all specimens. The rapid thermal annealed specimens at the relatively low temperatures were polycrystalline structure with the wurtzite hexagonal structures along (002). Rapid thermal annealing at high temperatures changed the polycrystalline structure to the single crystal of the zincblende cubic structures. Through the chemical analysis, the zincblende cubic structure was obtained in the specimen with the ratio of Zn/S near stoichiometry. ZnS thin film showed the shifted absorption edge towards the lower wavelength as annealing temperature increased, and the mean optical transmittance in the visible light range increased to 80.40% under 500℃ conditions.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.6
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• pp.267-271
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• 2010

Super hydrophilic and high transparent $TiO_2$ thin films were successfully fabricated by sol-gel method without an irradiation of UV light. In addition, surfactant Tween 80 was used for increasing the transmittance of the thin films. When the contents of Tween 80 in $TiO_2$ solution were 0.0, 1.0, 3.0, 5.0 wt%, the transmittance of $TiO_2$ thin films was ca. 74.31%, 74.25%, 79.69%, 81.99% at 550 nm wavelength, respectively. The contact angles of fabricated $TiO_2$ thin films with or without Tween 80 were from ca. $4.0^{\circ}$ to $4.5^{\circ}$. The $TiO_2$ thin films annealed over $400^{\circ}C$ showed anatase crystal structure and the photocatalytic property that decomposed methyl orange with UV irradiation. The surface morphologies, optical properties and contact angle of prepared thin films with different contents of Tween 80 were evaluated by field emission scanning electron microscope (FE-SEM), X-ray diffratometer (XRD), UV-Vis spectrophotometer and contact angle meter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.7
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• pp.6-13
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• 2006

Tin doped indium oxide(ITO) and Al doped zinc oxide(ZnO:Al) films, which are widely used as a transparent conductor in optoelectronic devices, were prepared by using the capacitively coupled DC magnetron sputtering method. ITO and ZnO:Al films with the optimum growth conditions showed each resistivity of $1.67{\times}10^{-3}[{\Omega}-cm],\;2.2{\times}10^{-3}[{\Omega}-cm]$ and transmittance of 89.61[%], 90.88[%] in the wavelength range of the visible spectrum. The two types of 5 inch-PDP cells with ZnO:Al and ITO transparent electrodes were made under the same manufacturing conditions. The PDP cell with ZnO:Al film was optimally operated in the mixing gas rate of Ne(base)-Xe(8[%]), and at gas pressure of 400[Torr]. It also shows the average measured brightness of $836[cd/m^2]$ at voltage range of $200{\sim}300$[V]. Luminous efficiency, one of the key parameter for high brightness and low power consumption, ranges from 1.2 to 1.6[lm/W] with increasing frequency of ac power supplier from 10 to 50[Khz]. The brightness and luminous efficiency are lower than those with ITO electrode by about 10[%]. However, these values are considered to be enough for the normal operation of PDP TV.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.11
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• pp.993-998
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• 2014

Silver (Ag) grid patterned PET substrates were manufactured by thermal roll-imprinting methods. We coated highly conductive layer (HCL) as a supply electrode on the Ag grid patterned PET in the three kinds of conditions. One was no-HCL without conductive PEDOT:PSS on the Ag grid patterned PET substrate, another was thin-HCL coated with ~50 nm thickness of conductive PEDOT:PSS on the Ag grid PET, and the other was thick-HCL coated with ~95 nm thickness of conductive PEDOT:PSS. These three HCLs in order showed 73.8%, 71.9%, and 64.7% each in transmittance, while indicating $3.84{\Omega}/{\Box}$, $3.29{\Omega}/{\Box}$, and $2.65{\Omega}/{\Box}$ each in sheet resistance. Fabrication of organic solar cells (OSCs) with HCL Ag grid patterned PET substrates showed high power conversion efficiency (PCE) on the thin-HCL device. The thick-HCL device decreased efficiency due to low open circuit voltage ($V_{OC}$). And the Ag grid pattern device without HCL had the lowest energy efficiency caused by quite low short current density ($J_{SC}$).

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.43.2-43.2
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• 2011

Single-walled carbon nanotubes (SWCNT) are transparent in the visible and show conductivity comparable to copper, and are environmentally stable. SWCNT films have high flexibility, conductivity and transparency approaching that indium tin oxide (ITO), and can be prepared inexpensively without vacuum equipment. Transparent conducting Films (TCF) of SWCNTs has the potential to replace conventional transparent conducting oxides (TCO, e.g. ITO) in a wide variety of optoelectronic devices, energy conversion and photovoltaic industry. However, the sheet resistance of SWCNT films is still higher than ITO films. A decreased in the resistivity of SWCNT-TCFs would be beneficial for such an application. We fabricated SWCNT sheet with $KAuBr_4$ on PET substrate. Arc-discharge SWCNTs were dispersed in deionized water by adding sodum dodecyl sulfate (SDS) as surfactant and sonicated, followed by the centrifugation. The dispersed SWCNT was spray-coated on PET substrate and dried on a hotplate at $100^{\circ}C$. When the spray process was terminated, the TCF was immersed into deionized water to remove the surfactant and then it was dried on hotplate. The TCF film was then treated with AuBr4-, rinsed with deionized water and dried. The surface morphology of TCF was characterized by field emission scanning electron microscopy. The sheet resistance and optical transmission properties of the TCF were measured with a four-point probe method and a UV-visible spectrometry, respectively. $HNO_3$ treated SWCNT films with Au nano-particles have the lowest 61 ${\Omega}$/< sheet resistance in the 80% transmittance. Sheet resistance was decreased due to the increase of the hole concentration at the washed SWCNT surface by p-type doping of $AuBr_4{^-}$.