• Clean Technology
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• v.18 no.1
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• pp.69-75
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• 2012

In this study, we executed an environmental impact assessment about recycling of ITO (Indium Tin Oxide), used for touch panel. ITO is mainly used to make transparent conductive coatings for touch and flat screen LCD (Liquid Crystal Display), ELD (Emitting Light Device), PDP (Plasma Display Panel). This demand is increasing little by little. but form current status, ITO is discarded than recycling. It is important to recycling ITO for national strategies about resource conservation, and reduce environmental burden. Also Landfill or incineration of ITO cloud be harmful to the human health in the long-term. Material Life Cycle Assessment method (MLCA) was conducted for comparison landfill and recycling of ITO. MLCA would provide more information for environmental issues and potential environmental impacts of ITO. The study includes two scenarios, the basic scenario is recycling of ITO (10, 20, 30%) and the other scenario is landfill of ITO. In addition, amount of carbon dioxide and energy were calculated.

• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.434-434
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• 2012

Despite recent efforts for fabricating flexible transparent conducting films (TCFs) with low resistance and high transmittance, several obstacles to meet the requirement of flexible displays still remain. Indium tin oxide (ITO) thin films, which have been traditionally used as the TCFs, have a serious obstacle in TCFs applications. SWNTs are the most appropriate materials for conductive films for displays due to their excellent high mechanical strength and electrical conductivity. Recently, it has been demonstrated that acid treatment is an efficient method for surfactant removal. However, the treatment has been reported to destroy most SWNT. In this work, the fabrication by the spraying process of transparent SWNT films and reduction of its sheet resistance by Au-ionic doping treatment on PET substrates is researched. Arc-discharge SWNTs were dispersed in deionized water by adding sodium dodecyl sulfate (SDS) as surfactant and sonicated, followed by the centrifugation. The dispersed SWNT was spray-coated on PET substrate and dried on a hotplate. 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 was doped with Au-ionic doping treatment, 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. This was confirmed and discussed on the XPS and UPS studies. We show that 87 ${\Omega}/{\Box}$ sheet resistances with 81% transmittance at the wavelength of 550 nm. The changes in electrical and optical conductivity of SWNT film before and after Au-ionic doping treatments were discussed. The effects of hole transport interface layer using Au-ionic doping SWNT on the performance of organic solar cells were investigated.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.928-934
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• 2002

Gallium doped Zinc Oxide(GZO) films were deposited by dc magnetron sputtering using a GZO ceramic target at various conditions such as substrate temperature (RT, 400), residual water pressure ($P_{H_2O}$; 1.61${\times}10^{-4}∼2.2{\times}10^{-3}$ Pa), introduction of $H_2$ gas (8.5%) and different magnetic field strengths(250, 1000G). GZO films deposited without substrate heating showed clear degradation in film crystallinity and electrical properties with increasing $P_{H_2O}$. The resistivity increased from 3.0${\times}10^{-3}$ to 3.1${\times}10^{-2}{\Omega}㎝$ and the grain size of the films decreased from 24 to 3 nm when PH2O was increased from 1.61${\times}10^{-4}$ to 2.2${\times}10^{-3}$ Pa. However, degradation in electrical properties with increasing $P_{H_2O}$ was not observed for the films deposited with introduction of 8.5% $H_2$. When magnetic field strength of the cathode increased from 250G to 1000G, crystallinity and electrical properties of GZO films improved remarkably about all the $P_{H_2O}$. This result could be attributed to the decrease in film damage caused by the decrease in plasma impedance.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.935-942
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• 2002

Gallium-doped ZnO (GZO) films were deposited on soda-lime glass substrate without heating using Ne, Ar, or Kr gas. Electrical properties of GZO films deposited at various total gas pressures were investigated for the film positions corresponding to the erosion region (region B) and outside the erosion region (region A) of the target. Region B showed high resistivity, which was attributed to the decrease in carrier density and Hall mobility, compared to region A. GZO films deposited using Ne gas showed the degradation in resistivity and crystallinity, whereas, GZO films deposited using Kr gas showed the improvement in resistivity and crystallinity. This degradation in film properties could be attributed to the film damage caused by the bombardment of high-energy particles. Especially, the energies of recoiled neutral atoms ($Ne^0,\;Ar^0,\;Kr^0$) calculated by Monte Carlo simulation corresponded to experimental results.

• Journal of the Korean Vacuum Society
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• v.19 no.4
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• pp.275-280
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• 2010

The influence of $O_2$-plasma treatment on $H_2$ post-treated BZO (ZnO:B) thin film using MOCVD (Metal-Organic Chemical Vapor Deposition) are investigated. An $O_2$-plasma treatment of the $H_2$ post-treated BZO thin films resulted in XRD peak of (100), (101) and (110). Also, electrical properties resulted in an increase in sheet resistance and work function. The weighted optical transmittance and haze at 300~1,100 nm of BZO thin films with $O_2$-plasma treatment on the $H_2$ post-treatment show approximately 86% and 15%, respectively.

• Korean Journal of Materials Research
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• v.24 no.10
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• pp.543-549
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• 2014

A zinc oxide (ZnO) hybrid structure was successfully fabricated on a glass substrate by metal organic chemical vapor deposition (MOCVD). In-situ growth of a multi-dimensional ZnO hybrid structure was achieved by adjusting the growth temperature to determine the morphologies of either film or nanorods without any catalysts such as Au, Cu, Co, or Sn. The ZnO hybrid structure was composed of one-dimensional (1D) nanorods grown continuously on the two-dimensional (2D) ZnO film. The ZnO film of 2D mode was grown at a relatively low temperature, whereas the ZnO nanorods of 1D mode were grown at a higher temperature. The change of the morphologies of these materials led to improvements of the electrical and optical properties. The ZnO hybrid structure was characterized using various analytical tools. Scanning electron microscopy (SEM) was used to determine the surface morphology of the nanorods, which had grown well on the thin film. The structural characteristics of the polycrystalline ZnO hybrid grown on amorphous glass substrate were investigated by X-ray diffraction (XRD). Hall-effect measurement and a four-point probe were used to characterize the electrical properties. The hybrid structure was shown to be very effective at improving the electrical and the optical properties, decreasing the sheet resistance and the reflectance, and increasing the transmittance via refractive index (RI) engineering. The ZnO hybrid structure grown by MOCVD is very promising for opto-electronic devices as Photoconductive UV Detectors, anti-reflection coatings (ARC), and transparent conductive oxides (TCO).

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.430.2-430.2
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• 2016

The front transparent conductive oxide (TCO) films in thin fill solar cell should exhibit high transparency, conductivity, good surface morphology and excellent light scattering properties. The light trapping phenomenon is limited due to random surface structure of TCO films. The proper control of surface structure and uniform cauliflower TCO films may be appropriate for efficient light trapping. We report light trapping scheme of ICP-RIE glass texturing by SF6/Ar plasma for high roughness and haze ratio of ITO films. It was observed that the variation of etching time, pattern size and Ar flow ratio during ICP-RIE process were important factors to improve the diffused transmittance and haze ratio of textured glass. The ICP-RIE textured glass showed low etching rates due to the presence of metal elements like Al, B, F and Na. The ITO films deposited on textured glass substrates showed the high RMS roughness and haze ratio in the visible wavelength region. The change in surface morphology showed negligible influence on electrical and structural properties of ITO films. The ITO films with high roughness and haze ratio can be used to improve the performance of thin film solar cells.

• Korean Journal of Materials Research
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• v.21 no.2
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• pp.120-124
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• 2011

Silicon heterojunction solar cells have been studied by many research groups. In this work, silicon heterojunction solar cells having a simple structure of Ag/ZnO:Al/n type a-Si:H/p type c-Si/Al were fabricated. Samples were fabricated to investigate the effect of transparent conductive oxide growth conditions on the interface between ZnO:Al layer and a-Si:H layer. One sample was deposited by ZnO:Al at low working pressure. The other sample was deposited by ZnO:Al at alternating high working pressure and low working pressure. Electrical properties and chemical properties were investigated by light I-V characteristics and AES method, respectively. The light I-V characteristics showed better efficiency on sample deposited by ZnO:Al by alternating high working pressure and low working pressure. Atomic concentrations and relative oxidation states of Si, O, and Zn were analyzed by AES method. For poor efficiency samples, Si was diffused into ZnO:Al layer and O was diffused at the interface of ZnO:Al and Si. Differentiated O KLL spectra, Zn LMM spectra, and Si KLL spectra were used for interface reaction and oxidation state. According to AES spectra, sample deposited by high working pressure was effective at reducing the interface reaction and the Si diffusion. Consequently, the efficiency was improved by suppressing the SiOx formation at the interface.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.105-109
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• 2007

In this paper, we fabricated TCO (transparent conductive oxide) electrode on flexible substrate in order to study effects of electrical and optical properties according to Al-doped ZnO(AZO) film thickness. The thickness of film was from 100 nm to 500 nm and was controlled by changing deposition time. We used High Resolution X-ray Diffractometer (HR-XRD) to analyze crystal structure and UV-visible spectrophotometer to measure property of optical transmittance, respectively. The surface images are obtained by using ESEM (Environment Scanning Electron Microscopy). In this experiment, all the AZO films deposited on flexible substrate show high transmittance over 90% and especially in the films with 400 nm and 500 nm thickness, the resistivity ($4.5{\times}10^{-3}\;{\Omega}-cm$) and optical bandgap energy (3.61 eV) are superior to the other films.