• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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• pp.29-32
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• 2000

Cerium oxide thin film has been proposed as a buffer layer between the ferroelectric film and the Si substrate in Metal-Ferroelectric-Insulator-Silicon (MFIS ) structures for ferroelectric random access memory (FRAM) applications. In this study, CeO$_2$thin films were etched with Cl$_2$/Ar gas combination in an inductively coupled plasma (ICP). The highest etch rate of CeO$_2$film is 230 $\AA$/min at Cl$_2$/(Cl$_2$+Ar) gas mixing ratio of 0.2. This result confirms that CeO$_2$thin film is dominantly etched by Ar ions bombardment and is assisted by chemical reaction of Cl radicals. The selectivity of CeO$_2$to YMnO$_3$was 1.83. As a XPS analysis, the surface of etched CeO$_2$thin films was existed in Ce-Cl bond by chemical reaction between Ce and Cl. The results of XPS analysis were confirmed by SIMS analysis. The existence of Ce-Cl bonding was proven at 176.15 (a.m.u.).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.29-32
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• 2000

Cerium oxide thin film has been proposed as a buffer layer between the ferroelectric film and the Si substrate in Metal-Ferroelectric-Insulator-Silicon (MFIS ) structures for ferroelectric random access memory (FRAM) applications. In this study, CeO$_2$ thin films were etched with Cl$_2$/Ar gas combination in an inductively coupled plasma (ICP). The highest etch rate of CeO$_2$ film is 230 $\AA$/min at Cl$_2$/(Cl$_2$+Ar) gas mixing ratio of 0.2. This result confirms that CeO$_2$ thin film is dominantly etched by Ar ions bombardment and is assisted by chemical reaction of Cl radicals. The selectivity of CeO$_2$ to YMnO$_3$ was 1.83. As a XPS analysis, the surface of etched CeO$_2$ thin films was existed in Ce-Cl bond by chemical reaction between Ce and Cl. The results of XPS analysis were confirmed by SIMS analysis. The existence of Ce-Cl bonding was proven at 176.15 (a.m.u.).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.62-65
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• 2005

We studied the nematic liquid crystal (NLC) alignment capability by the Ultraviolet (UV) alignment method on a-C:H thin-films, and investigated electro-optical performances of the UV aligned twisted nematic (TN)-liquid crystal display (LCD) with the UV exposure on a-C:H thin film surface. A good LC alignment by UV irradiation on a-C:H thin-film surfaces was achieved. Monodomain alignment of the UV aligned TN-LCD can be observed. The good electro-optical (EO) characteristics of the UV aligned TN-LCD was observed with oblique UV exposure on the a-C:H thin film surface for 1min.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.147.2-148
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• 2016

Light management technology is very important for thin film solar cells, which can reduce optical reflection from the surface of thin film solar cells or enhance optical path, increasing the absorption of the incident solar light. Using proper light trapping structures in hydrogenated amorphous silicon (a-Si:H) solar cells, the thickness of absorber layers can be reduced. Instead, the internal electric field in the absorber can be strengthened, which helps to collect photon generated carriers very effectively and to reduce light-induced loss under long-term light exposure. In this work, we introduced a chemical etching technology to make honey-comb textures on glass substrates and analyzed the optical properties for the textured surface such as transmission, reflection and scattering effects. Using ray optics and finite difference time domain method (FDTD) we represented the behaviors of light waves near the etched surfaces of the glass substrates and discussed to obtain haze parameters for the different honey-comb structures. The simulation results showed that high haze values were maintained up to the long wavelength range over 700 nm, and with the proper design of the honey-comb structure, reflection or transmission of the glass substrates can be enhanced, which will be very useful for the multi-junction (tandem or triple junction) thin film a-Si:H solar cells.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.2
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• pp.142-148
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• 2012

This study presents the assessment results of adhesive properties on the interface between a silicon wafer and nano-scale polymer thin film pattern through UAFM images by using the contact resonance frequency of the cantilever. For the experiment, we varied surface treatment processes for the silicon wafer and fabricated a 300nm polymer thin film pattern through lithography. Images from the optical microscope were used to compare the produced test specimens for adhesive condition and the critical load value from the nano scratch test was used to verify the adhesive condition of the nano pattern. Each test specimen resulted in a $1{\mu}m{\times}1{\mu}m$ surface image and subsurface adhesive image. Adhesive condition was evaluated by image contrast differences on the interface according to the changing amplitudes and phases of contact resonance frequency.

• Korean Journal of Materials Research
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• v.19 no.5
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• pp.245-252
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• 2009

Changes in the surface morphology and light scattering of textured Al doped ZnO thin films on glass substrates prepared by rf magnetron sputtering were investigated. As-deposited ZnO:Al films show a high transmittance of above 80% in the visible range and a low electrical resistivity of $4.5{\times}10^{-4}{\Omega}{\cdot}cm$. The surface morphology of textured ZnO:Al films are closely dependent on the deposition parameters of heater temperature, working pressure, and etching time in the etching process. The optimized surface morphology with a crater shape is obtained at a heater temperature of $350^{\circ}C$, working pressure of 0.5 mtorr, and etching time of 45 seconds. The optical properties of light transmittance, haze, and angular distribution function (ADF) are significantly affected by the resulting surface morphologies of textured films. The film surfaces, having uniformly size-distributed craters, represent good light scattering properties of high haze and ADF values. Compared with commercial Asahi U ($SnO_2$:F) substrates, the suitability of textured ZnO:Al films as front electrode material for amorphous silicon thin film solar cells is also estimated with respect to electrical and optical properties.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.121-122
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• 2006

Recently, poly-Si TFT-LCD starts to be mass produced using excimer laser annealing (ELA) poly-Si. The main reason for this is the good quality poly-Si and large area uniformity. We report the influence of channel length and width on poly-Si TITs performance. Transfer characteristics of n-channel poly-Si thin film transistors fabricated on polycrystalline silicon (poly-Si) thin film transistors (TFTs) with various channel lengths and widths of $2-30{\mu}m$ has been investigated. In this paper, we analyzed the data of n-type TFTs. We studied threshold voltage ($V_{TH}$), on/off current ratio ($I_{ON}/I_{OFF}$), saturation current (I_{DSAT}$), and transconductance ($g_m$) of n-channel poly-Si thin film transistors with various channel lengths and widths.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.6
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• pp.580-585
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• 2004

Silicon dioxide (SiO$_2$) is widely used as a gate dielectric material for thin film transistors (TFT) and semiconductor devices. In this paper, SiO$_2$ films were grown by APCVD(Atmospheric Pressure chemical vapor deposition) at the high temperature. Experimental investigations were carried out as a function of $O_2$ gas flow ratios from 0 to 200 1pm. This article presents the SiO$_2$ gate dielectric studies in terms of deposition rate, refrative index, FT-IR, C-V for the gate dielectric layer of thin film transistor applications. We also study defect passivation technique for improvement interface or surface properties in thin films. Our passivation technique is Forming Gas Annealing treatment. FGA acts passivation of interface and surface impurity or defects in SiO$_2$ film. We used RTP system for FGA and gained results that reduced surface fixed charge and trap density of midgap value.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.126-127
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• 2007

In this study, the fabrication technique of a plannar field emission structure with DLC were studied Electric properties of carbon film on silicon substrate in methanol solution was carried out with various current density, solution temperature and electrode spacing between anode and cathode. The DLC film deposited on the Si substrate, plannar $SiO_2$ was obtained due to the shape of bottom electrode.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.3
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• pp.428-435
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• 2002

Pyroelectric $Pb(Zr_{0.3}Ti_{0.7})O_3$ (PZT30/70) thin film IR detectors has been fabricated and characterised. The PZT30/70 thin film was deposited onto $Pt/Ti/Si_3N_4/SiO_2/Si$ substrate by the sol-gel process. Four different substrate conditions were studied for their effects on the pyroelectric responses of the IR detectors. The substrate conditions were the combinations of the Si etching and the Pt/Ti patterning. In the Si etched substrate, the $Si_3N_4/SiO_2$ composite layer was used as silicon etch-stop, and was used as the membrane to support the PZT pyroelectric film element as well. The measured pyroelectric current and voltage responses of detectors fabricated on the micro-machined thin $Si_3N_4/SiO_2$ membrane were two orders higher than those of the detectors on the bulk-silicon. For detectors on the membrane substrate, the Pt/Ti patterned detectors showed a 2-times higher pyroelectric response than that of not-patterned detectors. On the other hand, the pyroelectric response of the detectors on the not-etched Si substrate was almost the same, regardless of the Pt/Ti patterning. It was also found that the rise time strongly depended on the substrate thickness: the thicker the substrate was, the longer the rise-time.