• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.99-100
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• 2006

Silicon-on-insulator(SOI) MOSFET with SiGe/Si heterostructure channel is an attractive device due to its potent use for relaxing several limits of CMOS scaling, as well as because of high electron and hole mobility and low power dissipation operation and compatibility with Si CMOS standard processing. SOI technology is known as a possible solution for the problems of premature drain breakdown, hot carrier effects, and threshold voltage roll-off issues in sub-deca nano-scale devices. For the forthcoming generations, the combination of SiGe heterostructures and SOI can be the optimum structure, so that we have developed SOI n-MOSFETs with SiGe/Si heterostructure channel grown by reduced pressure chemical vapor deposition. The SOI n-MOSFETs with a SiGe/Si heterostructure are presented and their DC characteristics are discussed in terms of device structure and fabrication technology.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.12
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• pp.624-630
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• 2001

The trend of the regulations on environmental issues are getting tight. Responding to this trend new technologies such as moving electrodes, wide pitch and pulsed power supply are also introduced in the electrostatic precipitator(EP) systems. The introduction of wide pitch and moving electrodes enhances the system performance of the EPs by improving air-flow and by improving the ash reentrainment on rapping. The power supplies for the EPs developed up to date include thyristor-based dc or intermittent type, SMPS(switching mode power supply) type and the pulsed-power supply type. The use of the pulsed ones is known to improve dust-collecting efficiency of high resistivity ash and reduces back corona occurrence in the collecting plate. There are two kinds of pulsed-power supplies; one with pulsed transformers and the other with direct dc switching devices. The latter uses rotary spark gap switches or semiconductor switches. Both have the merits and demerits: the spark gap switches are simple and robust but has short life time, hence, high maintenance cost, whereas the semiconductor switches have long life time but are costly. In this study, A high voltage power supply with superimposing voltage pulse on dc source was developed for EPs. This study describes circuit topology, operating principle of the scheme, and analysis of experimental results on Dong-Hae Power Plant. The pulsed power supply consists of a variable dc power supply with ratings of 60kV, 800mA and pulse generator which is made of high voltage thyristor-diode switch strings, an LC resonant tank and a blocking inductor. The pulse generator generates variable pulse-voltage up to 70kV using a high frequency resonant inverter with a variable dc source. Two prototypes were built and tested on 250MW DongHae power plant to verify the possibility of the commercial use and the normal operation in the transient states.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.181-184
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• 2004

Organic semiconductors have attracted considerable attention due to their interesting physical properties followed by various technological applications in the area of electronics and opto-electronics. It has been a long time since organic solar cells were expected as a low-cost high-energy conversion device. Although practical use of them has not been achieved, technological progress continues. Morphology of the materials, organic/inorganic interface, metal cathodes, molecular packing and structural properties of the donor and acceptor layers are essential for photovoltaic response. We have fabricated solar-cell devices based on copper-phthalocyanine(CuPc) as a donor(D) and fullerene($C_{60}$) as an electron acceptor(A) with doped charge transport layers, and BCP as an exciton blocking layer(EBL). We have measured photovoltaic characteristics of the solar-cell devices using the xenon lamp as a light source.

• Journal of Power Electronics
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• v.16 no.2
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• pp.685-694
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• 2016

This paper presents a reliability assessment model for the power semiconductors used in wind turbine power converters. In this study, the thermal loadings at different timescales of wind speed are considered. First, in order to address the influence of long-term thermal cycling caused by variations in wind speed, the power converter operation state is partitioned into different phases in terms of average wind speed and wind turbulence. Therefore, the contributions can be considered separately. Then, in regards to the reliability assessment caused by short-term thermal cycling, the wind profile is converted to a wind speed distribution, and the contribution of different wind speeds to the final failure rate is accumulated. Finally, the reliability of an actual power converter semiconductor for a 2.5 MW wind turbine is assessed, and the failure rates induced by different timescale thermal behavior patterns are compared. The effects of various parameters such as cut-in, rated, cut-out wind speed on the failure rate of power devices are also analyzed based on the proposed model.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.376-378
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• 1994

The turn-off behavior of the GTO Thyristor by its nature differs very much from that of other power f semiconductor switching devices. So canful attention should be paid in designing the GTO snubber circuit. This paper presents the effect of turn-off snubber circuit elements on the switching characteristics of the GTO, and describes considerations and criteria for the selection of the snubber component values.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.339-342
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• 1998

Plasma etching of photoresist needs high etch rate, good uniformity and rae, good uniformity and low damage in low cost. ICP asher is expected to satisfy these requriement for next eneration semiconductor devices. ICPsimulator has been used to design the ashing chamber to redcue the development time and cost, and its results have been verified by QMS, OES and langmuir probe measurments. Plasma characteristics are monitored in terms of RF power and chamber pressure.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.106-107
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• 2003

The interest of THz technology has been growing fast due to the potential of its vast applications. Today´s THz technology pursues semiconductor based miniature electronic devices operating at undeveloped electromagnetic frequency band between 100 GHz and 10 THz. Tremendous research progresses on THz technology have been made for decades. However, it is limited in the power and performance of THz sources and systems for real applications. (omitted)

• Journal of Power Electronics
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• v.17 no.2
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• pp.561-569
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• 2017

Power converter design requires simulation accuracy. In addition to the requirement of accurate models of power semiconductor devices, this paper highlights the role of considering a very good description of the converter circuit layout for an accurate simulation of its electrical behavior. This paper considers a simple experimental circuit including one switching cell where a MOSFET transistor controls the diode under test. The turn-off transients of the diode are captured, over which the circuit wiring has a major influence. This paper investigates the necessity for accurate modeling of the experimental test circuit wiring and the MOSFET transistor. It shows that a simple wiring inductance as the circuit wiring representation is insufficient. An adequate model and identification of the model parameters are then discussed. Results are validated through experimental and simulation results.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.596-599
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• 1991

This paper describes a novel switching algorithm of series connected power semiconductors for high voltage applications. In order to improve the reliability and efficiency of high voltage static power converters, we study on the switching characteristics of series connected power semiconductors and then propose "a servo control of snubber capacitor value" for the dynamic voltage balancing under turn-off state in series connected power semiconductors. Finally, we illustrate the validity of this algorithm by computer simulation and experimental results.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.1
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• pp.1-10
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• 2007

In recent few years, low-power electronics has been a leading drive for technology developments nourished by rapidly growing market share. Mobile DRAM, as a fundamental block of hand-held devices, is now becoming a product developed by limitless competition. To support application specific mobile features, various new power-reduction schemes have been proposed and adopted by standardization. Tightened power budget in battery-operated systems makes conventional schemes not acceptable and increases difficulty of the circuit design. The mobile DRAM has successfully moved down to 1.5V era, and now it is about to move to 1.2V. Further voltage scaling, however, presents critical problems which must be overcome. This paper reviews critical issues in mobile DRAM design and various circuit schemes to solve the problems. Focused on analog circuits, bitline sensing, IO line sensing, refresh-related schemes, DC bias generation, and schemes for higher data rate are covered.