• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.237-237
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• 2006

P(VDF/TrFE(72/28) ultrathin films were used in the fabrication of Metal-Ferroelectric polymer-Metal (MFM) single bit device with special emphasis on uniform film surface, faster dipole switching time under applied external field and longer memory retention time. AFM and FTIR-GIRAS were complementary in analyzing surface crystalline morphology and the resultant change in chain orientation with varying thermal history. DC-EFM technique was used to 'write-read-erase' the data on the memory bit in a much faster time than P-E studies. The results obtained from this study will enable us to have a good understanding of the ferroelectric and piezoelectric behavior of P(VDF/TrFE)(72/28) thin films suitable for high density data storage applications.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.186-186
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• 2006

We report a new architecture for high efficiency polymer solar cells introducing a new concept of 'optical spacer' with new material. By implementing a novel solution-based titanium oxide ($TiO_{x}$) layer between the active layer and the electron collecting Al electrode, we invented a way to increase ${\sim}50\;%$ in power conversion efficiency compared to conventional polymer solar cells. Now the new devices exhibit ${\sim}6\;%$ power conversion efficiency, which is the highest value reported to date for a polymer based photovoltaic cell. The $TiO_{x}$ layer increases the efficiency by modifying the spatial distribution of the light intensity inside the device, thereby creating more photogenerated charge carriers in the bulk heterojunction layer.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.446-449
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• 2008

Organic light emitting diodes (OLEDs) with multiple organic layers were fabricated to obtain and to evaluate an equivalent resistance and an equivalent capacitance of OLED device. The staircase voltage with an increasing period and a constant period was designed and applied to the OLED. The resistance of OLED was found to decrease from $270\;k{\Omega}$ to $2\;K{\Omega}$ as applied voltage increased after turn on. The equivalent capacitance of OLED maintained unchanged at low voltage level and deceased after showing peak value as the applied voltage increased.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.928-931
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• 2008

Using 4,4'4"-tris(N-carbazolyl)-triphenylamine (TCTA) small molecule interlayer, we have fabricated efficient green PHOLED by solution process. The maximum current and power efficiency values of 33.7 cd/A and 19.6 lm/W are demonstrated, respectively. Results reveal a way to fabricate the PHOLED using TCTA interlayer by solution process, promising for efficient and simple manufacturing.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.521-522
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• 2008

An etch-less simple method was developed to fabricate two-dimensional nanostructures on glass substrate directly by using UV curable polymer resin and UV nanoimprint lithography in order to improve output coupling efficiency of OLEDs. OLEDs integrated on nanoimprinted substrates enhanced electro-luminance intensity by up to 50% compared with the conventional device.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.2
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• pp.47-49
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• 2004

Gate protection $SiN_x$ as an alternative to a conventional re-oxidation process in Dynamic Random Access Memory devices is investigated. This process can not only protect the gate electrode tungsten against oxidation, but also save the thermal budget due to the re-oxidation. The protection $SiN_x$ process is applied to the poly-Si gate, and its device performance is measured and compared with the re-oxidation processed poly-Si gate. The results on the gate dielectric integrity show that etch damage-curing capability of protection $SiN_x$ is comparable to the re-oxidation process. In addition, the hot carrier immunity of the $SiN_x$ deposited gate is superior to that of re-oxidation processed gate.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1401-1403
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• 2005

We present that the carrier balance can be improved by doping a hole transport layer of 4,4'- bis[N-(1-napthyl)-N-phenyl-amino]-biphenyl (${\alpha}$-NPD) with a hole blocking material of 2,9-dimethyl- 4,7-diphenyl-1,10-phenanthroline (BCP). The doping leads to disturb hole transport, which can enhance the balance of electron s and holes concentration in the emitting layer, aluminum tris(8 -hydroxyquinoline) (Alq3), resulting in enhanced electroluminescence (EL) quantum efficiency for the device with the doped ${\alpha}$-NPD.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.2
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• pp.102-109
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• 2007

We propose and experimentally demonstrate a ring resonator with sharp U-turns fabricated on a silicon-on-insulator (SOI) substrate; the resonator was designed as a key part of an optical, dynamic data storage device. We discuss the optical properties of the fabricated ring resonator from the viewpoint of equi-frequency-contour behavior in a dispersion space. We successfully characterize its optical characteristics on the basis of photonic crystal physics. It is suggested that the photonic ring resonator will be applicable to optical, dynamic memory devices for optical communication systems.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.06a
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• pp.262-262
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• 2003

Creating a new spin-based electronics (often called "spin-electronics" or "spintronics") is one of the hot topics in the current solid-state physics and electronics research. In order to utilize the spin degree of freedom in solids, particularly in semiconductors the current electronics is based on, we need to fabricate appropriate materials, understand and control the spin-dependent phenomena. In this ta1k, I will review the recent deve1opments of epitaxial ferromagnetic hetero structures based on semiconductors towards spintronics. This includes the semiconductor materials and hetero structures having high ferromagnetic transition temperature (III-V based alloy magnetic semiconductors, Mn-delta-doped magnetic semiconductors, and related heterostructures), spin-dependent transport and tunneling, and their device applications (tunneling magnetoresistance devices and three-terminal devices). Future issues and prospects will be also discussed.

• Journal of the Optical Society of Korea
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• v.13 no.2
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• pp.261-266
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• 2009

The angular dispersion-type non-scanning Fabry-Perot was applied to an ethanol-water mixture in order to investigate its acoustic properties such as the sound velocity and the absorption coefficient. The scattered light from the mixture was analyzed by using the charge-coupled-device area detector, which made the measurement time much shorter than that obtained by using the conventional scanning tandem multi-pass Fabry-Perot interferometer. The sound velocity showed a deviation from ultrasonic sound velocities at low temperatures accompanied by the increase in the absorption coefficient, indicating acoustic dispersion due to the coupling between the acoustic waves and some relaxation process. Based on a simplified viscoelastic theory, the temperature dependence of the relaxation time was obtained. The addition of water molecules to ethanol reduced the relaxation time, consistent with dielectric measurements. The present study showed that the angular dispersion-type Fabry-Perot interferometer combined with an area detector could be a very powerful tool in the real-time monitoring of the acoustic properties of condensed matter.