• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.53-56
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• 1998

Electroluminescent(EL) devices based on organic materials have been of great interest due to their possible applications for large-area flat-panel displays, where they are attractive because of their capability of multicolor emission, and low operation voltage. In this study, glass substrate/ITO/Eu(TTA)$_3$(Phen)/Al(A), glass substrate/ITO/TPD/Eu(TTA)$_3$(p-hen)/Al(B) and glass substrate/ITO/TPD/Eu(TTA)$_3$(phen)/AlQ$_3$/Al(C) structures were fabricated by vacuum evaporation method. where aromatic diamine(TPD) was used as a hole transporting material, Eu(TTA)$_3$(phen) as an emitting material. and tris(8-hydroxyquinoline)Aluminum(AlQ$_3$) as an electron transporting layer. Electroluminescent(EL) and I-V characteristics of Eu(TTA)$_3$(Phen) with a various thickness were investigated. This structure shows the red EL spectrum, which is almost the same as the PL spectrum of Eu(TTA)$_3$(phen). I-V characteristics of this structure show that turn-on voltage was 9V and current density was 0.01A/$\textrm{cm}^2$ at a dc operation voltage of 9V. Electrical transporting phenomena of these structures was explained using the trapped- charge-limited current model with I-V characteristics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.6
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• pp.458-464
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• 1998

This paper gives characterization of substrate and PZT(53/47) thin film deposited by metalorganic decomposition, which is concerned in deposition process and device fabrication process, to fabricate micro electro mechanical system (MEMS) device with piezoelectric material. The PZT thin films deposited by MOD at 700^{\circ}C$ for 30 minutes had a polycrystallinity, that is, no substrate dependence, while different interface were developed depending on the bottom electrodes. Such a structural variation could influence on not only the properties of the PZT film but also etching process for fabricating MEMS devices. Therefore the electrode structure is a very important factor in the deposition of the PZT film during etching process by HF acid for MEMS device with piezoelectric material. Piezoelectric coefficients of the PZT films on the different substrates were 40 and 80 pm/V at an applied voltage of 4V. Based in these results, it was possible for deposition of the PZT film by MOD to apply MEMS device fabrication process based on piezoelectricity after selection of proper bottom electrode.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.6
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• pp.428-435
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• 1998

SOI-like-bulk CMOS device is proposed, which having the advantages of SOI(Silicon On Insulator) and protects short channel effects efficiently with adding partial epitaxial process at standard CMOS process. SOI-like-bulk NMOS and PMOS with 0.25${\mu}{\textrm}{m}$ gate length have designed and optimized through analyzing the characteristics of these devices and applying again to the design of processes. The threshold voltages of the designed NMOS and PMOS are 0.3[V], -0.35[V] respectively and those have shown the stable characteristics under 1.5[V] gate and drain voltages. The leakage current of typical bulk-CMOS increase with shortening the channel length, but the proposed structures on this a study reduce the leakage current and improve the subthreshold characteristics at the same time. In addition, subthreshold swing value, S is 70.91[mV/decade] in SOI-like-bulk NMOS and 63.37[mV/ decade] SOI-like-bulk PMOS. And the characteristics of SOI-like-bulk CMOS are better than those of standard bulk CMOS. To validate the circuit application, CMOS inverter circuit has designed and transient & DC transfer characteristics are analyzed with mixed mode simulation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.613-617
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• 2002

The ceramic filters were developed using technology similar to that of quartz crystal and electromechanical filter. However, the key to this development involved the theoretical analysis of vibration modes and material improvements of piezoelectric ceramics. The primary application of ceramic filters has been for consumer-market use. Accordingly, a major emhpasis has involved mass production technology, leading to low-priced devices. A typical ceramic filter includes monolithic resonators and capacitors packaged in unique configurations. Nakazawa developed a double-mode resonator as two acoustically coupled single resonators. And he developed 10.7MHz crystal filters using multi-energy trapping mode of thickness shear vibration. He succeeded in realizing a two-pole band pass filter response without external inductance by splitting a dot electrode to creat coupled symmetric and antisymmetric vibration modes. Accordingly, the simulation for ceramic filter were important. So that, this paper were investigated the pass frequency of filter on the electrode length and thickness of ceramic.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.834-838
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• 2002

In this paper, we have fabricated 4H-SiC schottky diodes utilizing a metal-oxide overlap structure for electric filed termination. The barrier height and Ideality factor were measured by current-voltage, capacitance-voltage characteristics. Schottky barrier height(SBH) were 1.41ev for Ni and 1.35eV for Pt, 1.52eV for Pt/Ti at room temperature and Pt/Ti Schottky diode exhibited Ideality factor was 1.06 to 1.4 in the range of $25^{\circ}C{\sim}200^{\circ}C$. To improve the reverse bias characteristics, an edge termination technique is employed for Pt/Ti/4H-SiC Schottky rectifiers and the device show excellent characteristics with higher blocking voltage up to 780V compared with unterminated devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.642-645
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• 2002

Microwave dielectric properties of $ZnWO_4$ ceramic were investigated with calcination and sintering temperatures. The dielectric properties required for such application are high dielectric constant$(\varepsilon_r)$, high $Q{\times}f_o$ value and low temperature coefficient of resonant frequency$(\tau_f)$. These requirement correspond to necessities for size reduction, excellent frequency selectivity, good temperature stability of devices. $ZnWO_4$ ceramics could be sintered at low $1075^{\circ}C$, which was comparatively low temperature for microwave dielectrics. As a result, $ZnWO_4$ showed the dielectric constant of 13, quality factor($Q{\times}f_o$ value) of 22000 and 'temperature coefficient of resonant frequency$(\tau_f)$ of $-65{\pm}5ppm/^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.805-808
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• 2002

A carbon monoxide gas sensor utilizing Pt-SiC, Pt-SnO2-SiC diode structure was fabricated. Since the operating temperature for silicon devices in limited to 200oC, sensor which employ the silicon substrate can not at high temperature. In this study, CO gas sensor operating at high temperature which utilize SiC semiconductor as a substrate was developed. Since the SiC is the semiconductor with wide band gap. the sensor at above $700^{\circ}C$. Carbon monoxide-sensing behavior of Pt-SiC, Pt-SnO2-SiC diode is systematically compared and analyzed as a function of carbon monoxide concentration and temperature by I-V and ${\Delta}$I-t method under steady-state and transient conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.320-321
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• 2006

In this work, impedance Spectroscopic analysis was applied to study the effect of plasma treatment on the surface of indium-tin oxide (ITO) anodes using $CF_4g$ as and to model the equivalent circuit for organic light emitting diodes (OLEDs) with the $CF_4$ plasma treatment of ITO surface at the anodes. This device with ITO/TPD/$Alq_3$/LiF/Al structure can be modeled as a simple combination of a resistor and a capacitor. The $CF_4$ plasma treatment on the surface of ITO shifts the vacuum level of the ITO as a result of which the barrier height for hole injection at the ITO/organic interface is reduced. The Impedance spectroscopy measurement of the devices with the $CF_4$ plasma treatment on the surface of ITO anodes shows change of values in parallel resistance ($R_p$) and parallel capacitance ($C_p$).

• Transactions on Electrical and Electronic Materials
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• v.16 no.5
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• pp.234-240
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• 2015

Amorphous oxide-based thin-film transistors (TFTs) have drawn a lot of attention recently for the next-generation high-resolution display industry. The required field-effect mobility of oxide-based TFTs has been increasing rapidly to meet the demands of the high-resolution, large panel size and 3D displays in the market. In this regard, the current status and major trends in the high mobility oxide-based TFTs are briefly reviewed. The various approaches, including the use of semiconductor, dielectric, electrode materials and the corresponding device structures for realizing high mobility oxide-based TFT devices are discussed.

• Electrical & Electronic Materials
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• v.28 no.2
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• pp.25-33
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• 2015

Ruthenium (Ru) thin films were grown on thermally-grown $SiO_2$ substrates by atomic layer deposition (ALD) using a sequential supply of four kinds of novel zero-valent Ru precursors, isopropyl-methylbenzene-cyclohexadiene Ru(0) (IMBCHDRu, $C_{16}H_{22}Ru$), ethylbenzen-cyclohexadiene Ru(0) (EBCHDRu, $C_{14}H_{18}Ru$), ethylbenzen-ethyl-cyclohexadiene Ru(0) (EBECHDRu, $C_{16}H_{22}Ru$), and (ethylbenzene)(1,3-butadiene)Ru(0) (EBBDRu, $C_{12}H_{16}Ru$) and molecular oxygen (O2) as a reactant at substrate temperatures ranging from 140 to $350^{\circ}C$. It was shown that little incubation cycles were observed for ALD-Ru processes using these new novel zero-valent Ru precursors, indicating of the improved nucleation as compared to the use of typical higher-valent Ru precursors such as cyclopentadienyl-based Ru (II) or ${\beta}$-diketonate Ru (III) metallorganic precursors. It was also shown that Ru nuclei were formed after very short cycles (only 3 ALD cycles) and the maximum nuclei densities were almost 2 order of magnitude higher than that obtained using higher-valent Ru precursors. The step coverage of ALD-Ru was excellent, around 100% at on a hole-type contact with an ultra-high aspect ratio (~32) and ultra-small trench with an aspect ratio of ~ 4.5 (top-opening diameter: ~ 25 nm). The developed ALD-Ru film was successfully used as a seed layer for Cu electroplating.