• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.288-289
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• 2011

Indium Tin Oxide (ITO) is a typical highly Transparent Conductive Oxide (TCO) currently used as a transparent electrode material. Most widely used deposition method is the sputtering process for ITO film deposition because it has a high deposition rate, allows accurate control of the film thickness and easy deposition process and high electrical/optical properties. However, to apply high quality ITO thin film in a flexible microelectronic device using a plastic substrate, conventional DC magnetron sputtering (DMS) processed ITO thin film is not suitable because it needs a high temperature thermal annealing process to obtain high optical transmittance and low resistivity, while the generally plastic substrates has low glass transition temperatures. In the room temperature sputtering process, the electrical property degradation of ITO thin film is caused by negative oxygen ions effect. This high energy negative oxygen ions(about over 100eV) can be critical physical bombardment damages against the formation of the ITO thin film, and this damage does not recover in the room temperature process that does not offer thermal annealing. Hence new ITO deposition process that can provide the high electrical/optical properties of the ITO film at room temperature is needed. To solve these limitations we develop the Magnetic Field Shielded Sputtering (MFSS) system. The MFSS is based on DMS and it has the plasma limiter, which compose the permanent magnet array (Fig.1). During the ITO thin film deposition in the MFSS process, the electrons in the plasma are trapped by the magnetic field at the plasma limiters. The plasma limiter, which has a negative potential in the MFSS process, prevents to the damage by negative oxygen ions bombardment, and increases the heat(-) up effect by the Ar ions in the bulk plasma. Fig. 2. shows the electrical properties of the MFSS ITO thin film and DMS ITO thin film at room temperature. With the increase of the sputtering pressure, the resistivity of DMS ITO increases. On the other hand, the resistivity of the MFSS ITO slightly increases and becomes lower than that of the DMS ITO at all sputtering pressures. The lowest resistivity of the DMS ITO is $1.0{\times}10-3{\Omega}{\cdot}cm$ and that of the MFSS ITO is $4.5{\times}10-4{\Omega}{\cdot}cm$. This resistivity difference is caused by the carrier mobility. The carrier mobility of the MFSS ITO is 40 $cm^2/V{\cdot}s$, which is significantly higher than that of the DMS ITO (10 $cm^2/V{\cdot}s$). The low resistivity and high carrier mobility of the MFSS ITO are due to the magnetic field shielded effect. In addition, although not shown in this paper, the roughness of the MFSS ITO thin film is lower than that of the DMS ITO thin film, and TEM, XRD and XPS analysis of the MFSS ITO show the nano-crystalline structure. As a result, the MFSS process can effectively prevent to the high energy negative oxygen ions bombardment and supply activation energies by accelerating Ar ions in the plasma; therefore, high quality ITO can be deposited at room temperature.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.50-54
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• 1999

Plasma display panel is a potential candidate for HDTV, due to the fact that the screen size can easily be increased by a thick film technology. In this study, transparent dielectric materials which satisfied the requirements of dielectrics for PDP was developed using lead alumina borosilicate glasses. The Paste which had thixotropic behavior suitable for screen printing was made of this glass composition. the paste became more thixotropic as the particle size decreased. After firing, the cross sectional area of the thick film was analyzed by SEM. The voids in the thick film were removed using bimodal particle system. The dielectric thick film showed good adhesion characteristics.

• Journal of the Korean Ceramic Society
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• v.52 no.4
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• pp.290-293
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• 2015

The properties of the IZTO thin films on the glass were studied with a variation of the $SiO_2$ buffer layer thickness. $SiO_2$ buffer layers were deposited by plasma-enhanced chemical vapor deposition (PECVD) on the glass, and the In-Zn-Tin-Oxide (IZTO) thin films were deposited on the buffer layer by RF magnetron sputtering. All the IZTO thin films with the $SiO_2$ buffer layer are shown to be amorphous. Optimum $SiO_2$ buffer layer thickness was obtained through analyzing the structural, morphological, electrical, and optical properties of the IZTO thin films. As a result, the IZTO surface roughness is 0.273 nm with a sheet resistance of $25.32{\Omega}/sq$ and the average transmittance is 82.51% in the visible region, at a $SiO_2$ buffer layer thickness of 40 nm. The result indicates that the uniformity of surface and the properties of the IZTO thin film on the glass were improved by employing the $SiO_2$ buffer layer and the IZTO thin film can be applied well to the transparent conductive oxide for display devices.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.39.2-39.2
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• 2011

With the steady increase in the demand for flexible devices, mainly in display panels, researchers have focused on finding a novel material that have excellent electrical properties even when it is bended or stretched, along with superior mechanical and thermal properties. Graphene, a single-layered two-dimensional carbon lattice, has recently attracted tremendous research interest in this respect. However, the limitations in the growing method of graphene, mainly chemical vapor deposition on transition metal catalysts, has posed severe problems in terms of device integration, due to the laborious transfer process that may damage and contaminate the graphene layer. In addition, to lower the overall cost, a fabrication technique that supports low temperature and low vacuum is required, which is the main reason why solution-based process for graphene layer deposition has become the hot issue. Nonetheless, a direct deposition method of large area, few-layered, and uniform graphene layers has not been reported yet, along with a convenient method of patterning them. Here, we report an evaporation-induced technique for directly depositing few layers of graphene nanosheets with excellent uniformity and thickness controllability on any substrate. The printed graphene nanosheets can be patterned into desired shapes and structures, which can be directly applicable as flexible and transparent electrode. To illustrate such potential, the transport properties and resistivity of the deposited graphene layers have been investigated according to their thickness. The induced internal flow of the graphene solution during tis evaporation allows uniform deposition with which its thickness, and thus resistivity can be tuned by controlling the composition ratio of the solute and solvent.

• Journal of the Korean Ceramic Society
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• v.52 no.1
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• pp.72-76
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• 2015

150-nm-thick In-Zn-Tin-Oxide (IZTO) films were deposited by RF magnetron sputtering after a 10 to 50-nm-thick $SiO_2$ buffer layer was deposited by plasma enhanced chemical vapor deposition (PECVD) on polyethylene terephthalate (PET) substrates. The electrical, structural, and optical properties of the IZTO/$SiO_2$/PET films were analyzed with respect to the thickness of the $SiO_2$ buffer layer. The mechanical properties were outstanding at a $SiO_2$ thickness of 50 nm, with a resistivity of $1.45{\times}10^{-3}{\Omega}-cm$, carrier concentration of $8.84{\times}10^{20}/cm^3$, hall mobility of $4.88cm^2/Vs$, and average IZTO surface roughness of 12.64 nm. Also, the transmittances were higher than 80%, and the structure of the IZTO films were amorphous, regardless of the $SiO_2$ thickness. These results indicate that these films are suitable for use as a transparent conductive oxide for transparency display devices.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.341.1-341.1
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• 2014

In the advanced material for the next generation display device, transparent amorphous oxide semiconductors (TAOS) are promising materials as a channel layer in thin film transistor (TFT). The TAOS have many advantages for large-area application compared with hydrogenated amorphous silicon TFT (a-Si:H) and organic semiconductor TFT. For the reasonable characteristics of TAOS, The a-IGZO has the excellent performances such as low temperature fabrication (R.T~), high mobility, visible region transparent, and reasonable on-off ratio. In this study, we investigated how the electric characteristics and physical properties are changed as various oxygen ratio when magnetron sputtering. we analysis a-IGZO film by AFM, EDS and I-V measurement. decreasing the oxygen ratio, the threshold voltage is shifted negatively and mobility is increasing. Through this correlation, we confirm the effect of oxygen ratio. We fabricated the bottom-gate a-IGZO TFTs. The gate insulator, SiO2 film was grown on heavily doped silicon wafer by thermal oxidation method. a-IGZO channel layer was deposited by RF magnetron sputtering. and the annealing condition is $350^{\circ}C$. Electrode were patterned Al deposition through a shadow mask(160/1000 um).

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.336.2-336.2
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• 2014

Indium Tin Oxide (ITO) thin films are used as the Transparent Conducting Oxide (TCO), such as flat panel display, transparent electrodes, solar cell, touch screen, and various optical devices. ZnO has attracted attention as alternative materials to ITO film due to its resource availability, low cost, and good transmittance at the visible region. Recently, very thin film deposition is important. In order to minimize the damage caused by bending. However, ZnO thin film such as Ga-doped ZnO(GZO) has poor sheet resistance characteristics. To solve this problem, By adding the conductive metal on films can decrease the sheet resistance and increase the mobility of the films. In this study, We analyzed the electrical and optical characteristics of GZO/Ag/GZO (GAG) films by change in Ag and GZO thickness.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.390-392
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• 2013

The research was observed the characteristic of ZnO based oxide semiconductors for the transparent conducting display. The optical-physical properties of ZnO based oxide semiconductors) grown on p-Si wafer were presented. ZnO based oxide semiconductors was prepared by the RF magnetron sputtering system. The characteristic of ZnO based oxide semiconductorswas strongly influenced by the amount of localized electron state by the defects. The PL spectra moved to long wave number with increasing the defects in the film. The mobility of a-IGZO film was increased with increasing the oxygen gas flow rate. The resistivity of ZnO based oxide semiconductors was also related to the mobility of ZnO based oxide semiconductors, and the mobility increased at the sample with low resistivity. The electric characteristic of a-IGZO TFTs showed that it is an n-type semiconductor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.425-425
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• 2008

The transparent conducting oxides(TCOs) are widely used as electrodes for most flat panel display devices(FPDs), electrodes in solar cells and organic light emitting diodes(OLED). Among them, indium oxide materials are mostly used due to its high electrical conductivity and a high transmittance in the visible spectrum. The present study reports on a study of the electrical and optical properties of IGZO thin films prepared on glass and PET substrates by the combinational magnetron sputtering. We use the targets of IZO and Ga2O3 for the deposition process. In some case the deposition process is coupled with the End-Hall ion-beam treatment onto the substrates before the sputtering. In addition we control the deposition rate to optimize the film quality and to minimize the surface roughness. Then we investigate the effects of the Ar gas pressure and RF power during the sputtering process upon the electrical, optical and morphological properties of thin films. The properties of prepared IGZO thin films have been analyzed by using the XRD, AFM, a-step, 4-point probe, and UV spectrophotometer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.7
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• pp.738-746
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• 2004

Recently zinc oxide(ZnO) has emerged as one of the most promising transparent conducting films with a strong demand of low cost and high performance optoelectronic devices, ZnO film has many advantages such as high chemical and mechanical stabilities, and abundance in nature. In this paper, in order to obtain the excellent transparent conducting film with low resistivity and high optical transmittance for Plasma Display Pannel(PDP), aluminium doped zinc oxide films were deposited on Corning glass substrate by dc magnetron sputtering method. The effects of the discharge power and doping amounts of $Al_2$$O_3$ on the electrical and optical properties were investigated experimentally. Particularly in order to lower the electrical resistivity, positive and negative bias voltages were applied on the substrate, and the effect of bias voltage on the electrical properties of ZnO:Al thin film were also studied and discussed. Films with lowest resistivity of $4.3 \times 10 ^{-4} \Omega-cm$ and good transmittance of 91.46 % have been achieved for the films deposited at 1 mtorr, $400^{\circ}C$, 40 W, Al content of 2 wt% with a substrate bias of +30 V for about 800 nm in film thickness.