• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.103.1-103
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• 1998

• Journal of IKEEE
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• v.20 no.2
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• pp.181-183
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• 2016

In this work, the merged PiN Schottky(MPS) diodes based silicon carbide(SiC) have been optimized and designed for 1200V diodes by 2D-atlas simulation tool. We investigated the optimized characteristics of SiC MPS diodes such as breakdown voltage and specific on-resistance by varying the doping concentrations of P-Grid/epi-layer and space of P-Grid, which are the most important parameters. The breakdown voltage and specific on-resistance, based on Baliga's Figure Of Merit (BFOM), have been compared with and the SiC-based MPS diodes show improved BFOMs with low values of specific on-resistance and high breakdown voltage. It has been demonstrated 1,200 V SiC MPS diodes will find useful applications in high voltage energy-efficient devices.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.6
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• pp.309-313
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• 2013

Silicon carbide (SiC) has recently drawn an enormous industrial interest because of its useful mechanical properties such as thermal resistance, abrasion resistance and thermal conductivity at high temperature. Especially, high purity SiC is applicable to the fields of power semiconductor and lighting emitting diode (LED). In this work, high purity carbon powders as raw material for high purity SiC were prepared by a RF induction thermal plasma. Dodecane ($C_{12}H_{26}$) as hydrocarbon liquid precursor has been utilized for synthesis of high purity carbon powders. It is found that the filtercollected carbon powders showed smaller particle size (10~20 nm) and low crystallinity compared to the reactor-collected carbon powders. The purities of reactor-collected and filter-collected carbon powders were 99.9997 % (5N7) and 99.9993 % (5N3), respectively. In addition, the impurities of carbon powders synthesized by RF induction thermal plasma were mainly originated from the surrounding environment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.1
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• pp.71-74
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• 2006

In this paper, we investigated the characterization of silicon oxide(SiOx) thin film on Ethylene Terephthalate(PET) substrates by e-beam deposition for transparent barrier application. The temperature of chamber increases from $30^{\circ}C$ to $110^{\circ}C$, the roughness increase while the Water vapor transmission rate (WVTR) decreases. Under these conditions, the WVTR for PET can be reduced from a level of $0.57 g/m^2/day$ (bare subtrate) to $0.05 g/m^2/day$ after application of a 200-nm-thick $SiO_2$ coating at 110 C. A more efficient way to improve permeation of PET was carried out by using a double side coating of a 5-${\mu}m$-thick parylene film. It was found that the WVTR can be reduced to a level of $-0.2 g/m^2/day$. The double side parylene coating on PET could contribute to the lower stress of oxide film, which greatly improves the WVTR data. These results indicates that the $SiO_2$ /Parylene/PET barrier coatings have high potential for flexible organic light-emitting diode(OLED) applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.25-27
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• 2007

$Eu^{2+}$-doped $Ca_2Si_5N_8$ was grown on Si(100) substrate using metal-organic deposition (MOD) method and post-annealed at $900^{\circ}C$ in various atmosphere. Luminescence properties of these thin films were investigated with variations of $Eu^{2+}$-doped concentrations and annealing atmosphere. Thin film was formed with clean surface and uniform thickness of about 72 nm. From the measurements of luminescence properties of thin films, film must be post-annealed in nitrogen or mixture of nitrogen and hydrogen atmosphere to emit a sufficient light. For $Ca_{1.5}Eu_{0.5}Si_5N_8$ thin film annealed at $900^{\circ}C$ in nitrogen atmosphere, excitation band from 380 to 420 nm was detected with the maximum intensity at 404 nm and two broad emission bands from 530 to 630 nm were observed. These broad excitation and emission bands must be attributed to the nitrogen incorporations into the films. From the results, $Ca_{2-x}Eu_xSi_5N_8$ thin film has probability for next generation thin film lighting applications such as light emitting diode (LED) or electro-luminescence (EL).

• Journal of the Korean Ceramic Society
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• v.49 no.1
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• pp.111-117
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• 2012

Dependencies of thermal properties on the crystallization behavior of $0.9CaMgSi_2O_6-0.1MgSiO_3$ glass-ceramics were investigated as a function of heat-treatment temperature from $750^{\circ}C$ to $950^{\circ}C$. The crystallization behavior of the specimens depended on the heat-treatment temperature, which could be evaluated by differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) analysis by the Rietveld-reference intensity ratio (RIR) combined procedure. With an increase of the heat-treatment temperature, the thermal conductivity and thermal diffusivity of the heat-treated specimens increased. These results could be attributed to the increase of crystallization with heat-treatment temperature. However, the specific heat capacity of the heat-treated specimens was not affected by the heat-treatment temperature. The thermal conductivities measured from $25^{\circ}C$ to $100^{\circ}C$ were also discussed for application to lighting-emitting diode (LED) packages and substrate materials.

• Journal of Power Electronics
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• v.18 no.3
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• pp.892-901
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• 2018

SiC MOSFETs have been used to improve system efficiency in high frequency converters due to their extremely high switching speed. However, this can result in undesirable parasitic oscillations in practical systems. In this paper, models of the key components are introduced first. Then, theoretical formulas are derived to calculate the switching oscillation frequencies after full turn-on and turn-off in clamped inductive circuits. Analysis indicates that the turn-on oscillation frequency depends on the power loop parasitic inductance and parasitic capacitances of the freewheeling diode and load inductor. On the other hand, the turn-off oscillation frequency is found to be determined by the output parasitic capacitance of the SiC MOSFET and power loop parasitic inductance. Moreover, the shifting regularity of the turn-off maximum peak voltage with a varying switching speed is investigated on the basis of time domain simulation. The distortion of the turn-on current is theoretically analyzed. Finally, experimental results verifying the above calculations and analyses are presented.

• Journal of Radiation Protection and Research
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• v.37 no.2
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• pp.70-74
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• 2012

Silicon carbide (SiC) is a promising material for neutron detection at harsh environments because of its capability to withstand strong radiation fields and high temperatures. Two PIN-type SiC semiconductor neutron detectors, which can be used for nuclear power plant (NPP) applications, such as in-core reactor neutron flux monitoring and measurement, were designed and fabricated. As a preliminary test, MCNPX simulations were performed to estimate reaction probabilities with respect to neutron energies. In the experiment, I-V curves were measured to confirm the diode characteristic of the detectors, and pulse height spectra were measured for neutron responses by using a $^{252}Cf$ neutron source at KRISS (Korea Research Institute of Standards and Science), and a Tandem accelerator at KIGAM (Korea Institute of Geoscience and Mineral Resources). The neutron counts of the detector were linearly increased as the incident neutron flux got larger.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.5
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• pp.577-584
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• 2015

A photovoltaic (PV) system generates electricity by installing a solar energy array; therefore, the photovoltaic system can be easily exposed to external factors, which include environmental factors such as temperature, humidity, and radiation. These factors-as well as shading, in particular-lead to power degradation. When there is an output loss in the solar cell of a PV module package, the output loss is partly controlled by the bypass diode. As solar cells become highly efficient, the characteristics of series resistance and parallel resistance improve, and the characteristics of reverse voltage change. A bypass diode is connected in parallel to the string that is connected in series to the PV module. Ideally, the bypass diode operates when the voltage is -0.6[V] around. This study examines the bypass diode operating time for different types of crystalline solar cells. It compares the reverse voltage characteristics between the single solar cell and polycrystalline solar cell. Special modules were produced for the experiment. The shading rate of the solar cell in the specially made solar energy module was raised by 5% each time to confirm that the bypass diode was operating. The operation of the bypass diode is affected not only by the reverse voltage but also by the forward bias. This tendency was verified as the number of strings increased.

• Korean Journal of Materials Research
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• v.5 no.8
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• pp.1020-1025
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• 1995

The Schottky barrier hieght(SBH) of Au/n-Si(100) were investigated by current-voltage(I-V) and capacitance voltage(C-V) measurement within a temperature range of l00K∼300K. The values of SBH at room temperature obtained from these two measurements were (0.79${\pm}$0.02)eV. The SBH obtained from the C-V measurement was temperature independent, while that obtained from the I-V measurement decreased linearly with decreasing temperature. This indicates that the Schottky diode has deviated from the thermionic emission theory at low-temperature, Thus, other current transport processes were considered and the contribution of recombination current was dominant at low temperature. We found that it leads to a lower SBH value. Thus, the conflicating results between C-V and I-V measurement were explained, C-V measurement is believed to yield mare reliable SBH values in present study since it is not affected by the current transport uncertainties.