• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.495-498
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• 2009

To improve the efficiency of the high voltage cable for BLU(backlight unit) of TFT-LCD(Thin Film Transistor-Liquid Crystal Display), the analysis for the trial products(UL3239, UL3633) is conducted by using SEM(scanning electron microscope) and EDX(Energy Dispersive X-ray Spectroscopy). The result that it is possible to accumulate the know-how to about stranding pitch through effective improvement of stranding process. The troubles which are the badness of withstanding voltage and tensile strength etc. are solved by development of excellent material. Furthermore, phenomenon of conductor unfasten in the harness work is solved by improvement of the stranding wire process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04a
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• pp.165-168
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• 2000

An active-matrix LCD using thin film transistors (TFT) has been widely recognized as having potential for high-quality color fiat-panel displays. Pixel-Design Array Simulation Tool (PDAST) was used to profoundly understand the gate signal distortion and pixel charging capability, which are the most critical limiting factors for high-quality TFT-LCDs. In addition, PDAST can estimate voltage distributions in common electrode which can affect pixel voltage and feed-through voltage. Since PDAST can simulate the gate, data and the pixel voltages of a certain pixel on TFT array at any time and at any location on an array, the effect of common electrode voltage can be effectively analyzed. The information obtained from this study could be utilized to design the larger area and finer image quality panel.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.90-93
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• 1996

The conduction mechanisms of the off-current in low temperature ($\leq$600$^{\circ}C$) processed polycrystalline silicon thin film transistors (LTP poly-Si TFT's) has been systematically studied. Especially, the temperature and bias dependence of the off-current between unpassivated and passivated poly-Si TFT's was investigated and compared. The off-current of unpassivated poly-Si TFT's is due to a resistive current at low gate and drain voltage, thermal emission current at high gate, low drain voltage, and field enhanced thermal emission current in the depletion region near the drain at high gate and drain voltage. After hydrogenation, it was observed that the off-currents were remarkably reduced by plasma-hydrogenation. It was also observed that the off-currents of the passivated poly-Si TFT's are more critically dependent on temperature rather than electric field.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.2
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• pp.312-317
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• 1994

We studied the fabrication and electrical characteristics of high voltage hydrogenerated amorphous silicon thin film transistor using plasma enchanced chemical vapor deposition(PECVD). The device shows 2500${\AA}$ SiOS12T, 400-1500${\AA}$ a-Si tickness, 350V output voltage and 9.55${\times}$10S04T average on/off current ratio. We found that the leakage current of high voltage TFT occurred 0-70V drain voltage. As the leakage current depend on the a-Si thickness, the leakage current of high voltage TFT decreased by reduction of the a-Si thickness.

• Electrical & Electronic Materials
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• v.9 no.10
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• pp.1008-1012
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• 1996

I-V, C-V characteristics of inverted staggered type hydrogenerated amorphous silicon thin film transistor(a-Si:H TFT) was studied and experimentally verified. The results show that the log-log plot of drain current increased by voltage increase. The saturated drain current of DC output characteristics increased at a fixed gate voltage. According to the increase of gate voltage, activation energy of electron and the increasing width of Id at high voltage were decreased. Id saturation current saturated at high Vd over 4.5V, Vg-ld hysteresis characteristic curves occurred between -15V and 15V of Vg. Hysteresis current decreased at low voltage of -15V and increased at high voltage of 15V.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.4
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• pp.292-297
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• 2003

We fabricated a single crystal silicon thin film transistor for active matrix organic light emitting displays(AMOLEDs) using silicon on insulator wafer (SOI wafer). Poly crystal silicon thin film transistor(poly-Si TFT) Is actively researched and developed nowsdays for a pixel switching devices of AMOLEDs. However, poly-Si TFT has some disadvantages such as high off-state leakage currents and low field-effect mobility due to a trap of grain boundary in active channel. While single crystal silicon TFT has many advantages such as high field effect mobility, low off-state leakage currents, low power consumption because of the low threshold voltage and simultaneous integration of driving ICs on a substrate. In our experiment, we compared the property of poly-Si TFT with that of SOI TFT. Poly-Si TFT exhibited a field effect mobility of 34 $\textrm{cm}^2$/Vs, an off-state leakage current of about l${\times}$10$\^$-9/ A at the gate voltage of 10 V, a subthreshold slope of 0.5 V/dec and on/off ratio of 10$\^$-4/, a threshold voltage of 7.8 V. Otherwise, single crystal silicon TFT on SOI wafer exhibited a field effect mobility of 750 $\textrm{cm}^2$/Vs, an off-state leakage current of about 1${\times}$10$\^$-10/ A at the gate voltage of 10 V, a subthreshold slope of 0.59 V/dec and on/off ratio of 10$\^$7/, a threshold voltage of 6.75 V. So, we observed that the properties of single crystal silicon TFT using SOI wafer are better than those of Poly Si TFT. For the pixel driver in AMOLEDs, the best suitable pixel driver is single crystal silicon TFT using SOI wafer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.05a
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• pp.137-141
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• 1993

We studied the fabrication and electrical characteristics of high voltage hydrogenerated amorphous silicon thin film transistor using glow discharge plasma enchanced chemical vapor deposition (GDPECVD) with $2500{\AA}\;SiO_2$, $400-1500{\AA}$ a-Si thickness, 350V output voltage, 100V input voltaege, and $9.55{\times}10^4$ average on/off ratio. We found that leakage current of high voltage TFT occured 0-70V drain voltage.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.3
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• pp.279-284
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• 2014

This paper proposes a novel OLED pixel circuit to compensate the threshold voltage variation of p-channel low temperature polycrystalline silicon thin-film transistors (LTPS TFTs). The proposed 5-TFT OLED pixel circuit consists of 4 switching TFTs, 1 OLED driving TFT and 1 capacitor. One frame of the proposed pixel circuit is divided into initialization period, threshold voltage sensing and data programming period, data holding period and emission period. SmartSpice simulation results show that the maximum error rate of OLED current is -4.06% when the threshold voltage of driving TFT varies by ${\pm}0.25V$ and that of OLED current is 9.74% when the threshold voltage of driving TFT varies by ${\pm}0.50V$. Thus, the proposed 5T1C pixel circuit can realize uniform OLED current with high immunity to the threshold voltage variation of p-channel poly-Si TFT.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1176-1178
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• 2007

A novel integrated a-Si:H gate driver with high reliability has been designed and simulated. Since the a-Si:H TFT is easily degraded by gate bias stress, we should optimize the circuit considering the threshold voltage shift. The conventional circuit shows voltage drop at the input stage by threshold voltage of the TFT, however, the proposed circuit dose not shows voltage drop and keeps constant regardless of threshold voltage shift of the TFT.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1745-1747
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• 2000

TFT-LCD simulator, PDAST(Pixel Design Array Simulation Tool) could simulate the effect of the variation on the pixel characteristics. Since feed-through voltage in TFT-LCD can be a serious problem to pixel voltage characteristics, it should be compensated. It is applicable to various kinds of TFT-LCDs and can be used to calculate the spontaneous part of common electrode voltage accurately. Also, PDAST can estimate pixel voltage according to various inversion methods. It allows high-speed calculation and the information obtained from this study could be utilized to design the larger area and finer image quality panel.