• Journal of the Korean Applied Science and Technology
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• v.16 no.3
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• pp.249-254
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• 1999

The N-docosyl N'-methyl viologen-$(TCNQ)_2$, (DMVT) was synthesized. We investigated the ${\pi}-A$ isotherm of DMVT to find the optimal deposition condition. Temperature-dependent current-voltage characteristics of the DMVT LB films shows that there is an increase in conductivity at 330K or so. The in-plane electrical conductivity at room temperature is in the range of $10^{-7}{\sim}10^{-6}S/cm$. From the plot of logarithmic conductivity as a function of reciprocal temperature, two types of activation energies, 0.04eV and 0.73eV, were obtained depending on the temperature range. The Ohmic behaviour was observed below 0.6V and the Schottky effect was confirmed at $2.5{\sim}6V$, when the I-V characteristics was measured with Al/LB film/Al structure. I-V measurement for Al/LB film/ITO structure showed the asymmetrical I-V relationship, which resulted from the rectification property.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.1
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• pp.40-45
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• 2008

We developed small molecular organic nonvolatile $4F^2$ memory cells using metal layer evaporation followed by $O_2$ plasma oxidation. Our memory cells sandwich an upper ${\alpha}$-NPD layer, Al nanocrystals surrounded by $Al_2O_3$, and a bottom ${\alpha}$-NPD layer between top and bottom electrodes. Their nonvolatile memory characteristics are excellent: the $V_{th},\;V_p$ (program), $V_e$ (erase), memory margin ($I_{on}/I_{off}$), data retention time, and erase and program endurance were 2.6 V, 5.3 V, 8.5 V, ${\approx}1.5{\times}10^2,\;1{\times}10^5s$, and $1{\times}10^3$ cycles, respectively. They also demonstrated symmetrical current versus voltage characteristics and a reversible erase and program process, indicating potential for terabit-level nonvolatile memory.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.11
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• pp.894-901
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• 1991

Contact-type linear image sensors have been fabricated by means of RF glow discharge decomposition method of silane and hydrogen mixtures. The dependences of the electrical and optical properties of these sensor on thickness, RF power, substrate temperature and ambient gas pressure have been investigated. the ITO/i-a-Si:H/Al structure film shows photosensitivity of 0.85 and photocurrent to dark current ratio ($I_{ph}/I_{d}$) of 150 at 5V bias voltage under 200${\mu}W/cm^[2}$ red light intensity. Under 200${\mu}W/cm^[2}$ green light intensity, the ratio is 100. In order to investigate photocarrier transport mechanism and to obtain ${\mu}{\gamma}$ product we have measured the I-V characteristics of these sensors favricated with several different deposition parameters under various light sources. The linear inage sensor for document reading has been operated under reverse bias condition with green light source, resulting in ${\mu}{\gamma}$ product of about 1.5$[\times}10^{-9}cm^{2}$/V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.295-299
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• 1996

In order to investigate the relation between the microstructure and the V-I characteristics of HTSC wire, single and 19 filamentary silver-sheathed Bi2223 tapes were fabricated using the powder-in-tube method. Higher J$\_$c/ at 77.3 K(0 T) and 4.2 K(in magnetic field) can be achieved for the 19 filamentary Bi tape, comparing the single filamentary tape. However, the I$\_$c/ distribution of 19 filamentary Bi2223 tape was found to be wider by analyzing the curve obtained from 2nd differential of V-I data. This was considered to be resulted from worse uniformity of oxide filament due to severe cold working.

• Journal of Electrical Engineering and Technology
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• v.4 no.1
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• pp.111-117
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• 2009

This paper presents the characteristics of leakage currents flowing through zinc oxide (ZnO) surge arrester elements under the combined direct-current (DC) and 60 Hz alternating-current (AC) voltages. The current-voltage characteristic curves (I-V curves) of the commercial ZnO surge arrester elements were obtained as a function of the voltage ratio a. At constant peak value of the combined DC and AC voltage, the resistive leakage current of the ZnO blocks was significantly increased as the voltage ratio $\alpha$ increased. The I-V curves under the combined DC and AC voltages were placed between the pure DC and AC characteristics, and the cross-over phenomenon in both the I-V curves and R-V curves was observed at the low current region. The ZnO power dissipation for DC voltages was less than that for AC voltage in the pre-breakdown region and reversed at higher voltages.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.4
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• pp.607-612
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• 1994

The static and dynamic model of IGBT for the SPICE simulation has been successfully developed. The various circuit model parameters are extracted from the I-V and C-V characteristics of IGBT and implemented into our model. The static model of IGBT consists of the MOSFET, bipolar transistor and series resistance. The parameters to be extracted are the threshold voltage of MOSFET, current gain $\beta$ of bipolar transistor, and the series resistance. They can be extracted from the measured I-V characteristics curve. The C-V characteristics between the terminals are very important parameters to determine the turn-on and turn-off waveform. Especially, voltage dependent capacitance are polynomially approximated to obtain the exact turn-on and turn-off waveforms. The SPICE simulation results employing new model agree well with the experimental values.

• Transactions on Electrical and Electronic Materials
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• v.8 no.4
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• pp.170-173
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• 2007

Organic field-effect transistors (OFETs) are of interest for use in widely area electronic applications. We fabricated the organic field-effect transistor based a copper phthalocyanine (CuPc) as an active layer on the silicon substrate. The CuPc FET device was made a topcontact type and the substrate temperature was room temperature and $150^{\circ}C$. The CuPc thickness was 40 nm, and the channel length was $50{\mu}m$, channel width was 3 mm. We observed the typical current-voltage (I-V) characteristics and capacitance-voltage (C-V) in CuPc FET and we calculated the effective mobility with each device. Also, we observed the AFM images with different substrate temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.59-62
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• 1999

Inception and propagation of electrical tree and properties of Partial discharge(PD) pulses accompanying with tree as a function of needle tip radius in low density polyethylene were discussed. To study on these characteristics in different tip radius, we used specimens with needle-plane electrode system made of LDPE, observed inception and propagation of electrical tree by optical microscope with computer and investigated the characteristics of the phase resolved PD pulses accompanying with propagation of electrical tree. The PD quantities detected and analysed were PD magnitude, mean phase angle, average discharge, and the statistical characteristics of the PD pulses. As the tip radius ${\gamma}$ increases, tree inception stress E$\sub$i/ converges to constance value. This result suggests that tree inception stress E$\sub$i/ increases due to stress relaxation when the tip radius is small. Branch-type electrical tree was formed When E$\sub$i/ is 640-750[kV/mm]. bush-type electrical tree when E$\sub$i/ is 370∼400[kV/mm], branch-like electrical tree when E$\sub$i/ is 370-400[kV/mm].

• Bulletin of the Korean Mathematical Society
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• v.22 no.2
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• pp.121-126
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• 1985

D.K. Harrison [5] has shown that if R and S are fields of characteristic different from 2, then two Witt rings W(R) and W(S) are isomorphic if and only if W(R)/I(R)$^{3}$ and W(S)/I(S)$^{3}$ are isomorphic where I(R) and I(S) denote the fundamental ideals of W(R) and W(S) respectively. In [1], J.K. Arason and A. Pfister proved a corresponding result when the characteristics of R and S are 2, and, in [9], K.I. Mandelberg proved the result when R and S are commutative semi-local rings having 2 a unit. In this paper, we prove the result when R and S are 2-fold full rings. Throughout this paper, unless otherwise specified, we assume that R is a commutative ring having 2 a unit. A quadratic space (V, B, .phi.) over R is a finitely generated projective R-module V with a symmetric bilinear mapping B: V*V.rarw.R which is nondegenerate (i.e., the natural mapping V.rarw.Ho $m_{R}$ (V, R) induced by B is an isomorphism), and with a quadratic mapping .phi.:V.rarw.R such that B(x,y)=(.phi.(x+y)-.phi.(x)-.phi.(y))/2 and .phi.(rx)= $r^{2}$.phi.(x) for all x, y in V and r in R. We denote the group of multiplicative units of R by U(R). If (V, B, .phi.) is a free rank n quadratic space over R with an orthogonal basis { $x_{1}$, .., $x_{n}$}, we will write < $a_{1}$,.., $a_{n}$> for (V, B, .phi.) where the $a_{i}$=.phi.( $x_{i}$) are in U(R), and denote the space by the table [ $a_{ij}$ ] where $a_{ij}$ =B( $x_{i}$, $x_{j}$). In the case n=2 and B( $x_{1}$, $x_{2}$)=1/2, we reserve the notation [ $a_{11}$, $a_{22}$] for the space.the space.e.e.e.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.3
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• pp.487-493
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• 1997

Ti/sic(4H) Schottky barrier diodes were fabricated. The donor concentration and the built-in potential obtained by capacitance-voltage(C-V) measurement was about $2.0{\times}10^{15}{\textrm}{cm}^{-3}$ and 0.65 V, respectively. The ideality factor of 1.07 was obtained from the slope of current-voltage(I-V) characteristics at low current density. The breakdown field under the reverse bias voltage was about $1.7{\times}10^3V/{\textrm}{cm}$ and was very high. The barrier height of Ti for SiC(4H) was 0.91 V, which was determined by the analysis of the saturation current-temperature and the C-V characteristics.