• JSTS:Journal of Semiconductor Technology and Science
• /
• v.14 no.5
• /
• pp.594-600
• /
• 2014

A threshold voltage compensation pixel circuit was developed for active-matrix organic light emitting diodes (AMOLEDs) using amorphous indium-gallium-zinc-oxide thin-film transistors (a-IGZO-TFTs). Oxide TFTs are n-channel TFTs; therefore, we developed a circuit for the n-channel TFT characteristics. The proposed pixel circuit was verified and proved by circuit analysis and circuit simulations. The proposed circuit was able to compensate for the threshold voltage variations of the drive TFT in AMOLEDs. The error rate of the OLED current for a threshold voltage change of 3 V was as low as 1.5%.

• Journal of Electrical Engineering and Technology
• /
• v.6 no.4
• /
• pp.539-542
• /
• 2011

Thin-film transistors (TFTs) are fabricated using an amorphous indium gallium zinc oxide (a-IGZO) channel layer by rf-magnetron sputtering. Oxygen partial pressure significantly changed the transfer characteristics of a-IGZO TFTs. Measurements performed on a-IGZO TFT show the change of threshold voltage in the transistor channel layer and electrical properties with varying $O_2$ ratios. The device performance is significantly affected by adjusting the $O_2$ ratio. This ratio is closely related with the modulation generation by reducing the localized trapping carriers and defect centers at the interface or in the channel layer.

• Journal of Information Display
• /
• v.11 no.4
• /
• pp.160-164
• /
• 2010

Organic light-emitting devices (OLEDs) have shown superior characteristics and are expected to dominate the nextgeneration flat-panel displays. Active-matrix organic light-emitting diode (AMOLED) displays, however, have stringent demands on the performance of the backplane. In this paper, the development of thin-film transistors (TFTs) based on indium gallium zinc oxide (IGZO) on both Gen 1 and 6 glasses, and their decent characteristics, which meet the AMOLED requirements, are shown. Further, several display prototypes (e.g., 2.4" AMOLED, 2.4" transparent AMOLED, and 32" AMLCD) using IGZO TFTs are demonstrated to confirm that they can indeed be strong candidates for the next-generation TFT technology not only of AMOLED but also of AMLCD (active-matrix liquid crystal display).

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.1351-1354
• /
• 2006

In this paper, we study the effect of substrate temperature on property of Ga doped ZnO (GZO) thin film for transparent conductive oxide (TCO).GZO thin films have been deposited on corning glass 1737 by D.C. magnetron sputtering. We investigated the structural and electrical properties of GZO films using the X-Ray Diffractometer(XRD), Field Emission Scanning Electron Microscopy(FESEM) and 4-points probe .

• Journal of the Korean Ceramic Society
• /
• v.55 no.4
• /
• pp.325-336
• /
• 2018

Perovskite solar cells (PSCs) are a new class of photovoltaic devices, which have attracted significant attention due to their remarkable optoelectrical properties, including high absorption coefficients, high carrier mobilities, long carrier diffusion lengths, tunable bandgaps, low cost, and facile fabrication. PSCs have reached efficiencies of 22.70% and 18.36% on rigid fluorine-doped tin oxide and poly(ethylene terephthalate) substrates, respectively; these are comparable to those of single-crystal silicon and copper-indium-gallium-selenium solar cells. Over the past eight years, the photo conversion efficiency of PSCs has been significantly improved by device-architecture adjustments, and absorber and electron/hole transport layer optimization. Each layer is important for the performance of PSCs; hence, we discuss achievements in flexible perovskite solar cells (FPSCs), covering electron/hole-transport materials, electrode materials. We give a comprehensive overview of FPSCs and put forward suggestions for their further development.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.465-465
• /
• 2013

Inorganic 물질인 SiO2 dielectric 위에 organic dielectric PVP (4-vinyphenol)를 spin coating으로 올려, inorganic/organic dielectric 형태의 double layer구조로 High-performance amorphous indiumgallium zinc oxide thin-film transistors (IGZO TFT)를 제작하여 보았다. SiO2 dielectric을 buffer layer로 80 nm, PVP는 10Wt% 400 nm로 구성하였으며, 200 nm single SiO2 dielectric과 동일한 수준의 leakage current 특성을 MIM Capacitor 구조를 통해서 확인할 수 있었다. 이 소자의 장점은 용액공정의 도입으로 공정 시간의 단축 및 원가 절감을 이룰 수 있으며, dielectric과 channel 사이의 균일한 interface의 형성으로 interface trap 개선 및 Yield 향상의 장점을 갖는다. 우리는 실험을 통해서 SiO2 buffer layer가 수직 electric field에 의한 leakage current을 제어하고, PVP dielectric은 interface를 개선하는 것을 확인하였다. Vth의 negative shift 및 slope의 향상으로 구동전압이 줄어들고, 균일한 I-V Curve 형성을 통해서 Process Yield의 향상을 확인하였다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.1002-1004
• /
• 2009

Solution-processed indium-gallium-zinc-oxide thin-film transistors were fabricated by sol-gel method. By a combinatorial study of InGaZnO multi-component system, optimum molar ratio of In, Ga, and Zn has been selected. By adjusting the In:Ga:Zn molar ratio, TFTs with field-effect mobility of 0.5 ~ 1.5 $cm^2$/V-s, threshold voltage of -5 ~ 5 V, and subthreshold slope of 1.5 ~ 2.5 V/decade were achieved.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08a
• /
• pp.640-643
• /
• 2007

The effect of plasma damage was investigated on amorphous gallium-indium-zinc oxide (a-GIZO) films and transistors. Ion-bombardment by plasma process affects to turn semiconductor to conductor materials and plasma radiation may degrade to transistor electrical properties. All damages are easily recovered with a $350^{\circ}C$ thermal annealing.

• Journal of the Semiconductor & Display Technology
• /
• v.8 no.4
• /
• pp.65-69
• /
• 2009

Carbon nanotubes (CNTs) were coated with undoped zinc oxide (ZnO) or 5 wt% gallium-incorporated ZnO (GZO) using various deposition conditions. The CNTs were directly grown on conical-type tungsten substrates at $700^{\circ}C$ using inductively coupled plasma-chemical vapor deposition. The pulsed laser deposition technique was used to deposit the ZnO and GZO thin films with very low stress. Field-emission scanning electron microscopy and high-resolution transmission electron microscopy were used to monitor the variations in the morphology and microstructure of CNTs prior to and after ZnO or GZO coating. The formation of ZnO and GZO films on CNTs was confirmed using energy-dispersive x-ray spectroscopy. In comparison to the as-grown (uncoated) CNT emitter, the CNT emitter that was coated with a thin (10 nm) GZO film showed remarkably improved field emission characteristics, such as the emission current of $325\;{\mu}A$ at 1 kV and the threshold field of $1.96\;V/{\mu}m$ at $0.1\;{\mu}A$, and it also exhibited the highly stable operation of emission current up to 40 h.

• Journal of the Korean Ceramic Society
• /
• v.51 no.3
• /
• pp.156-161
• /
• 2014

Gallium oxide ($Ga_2O_3$) powders were synthesized using a precipitation method and a polymerized complex method. TG-DSC, SEM, and XRD were performed to investigate the phase and morphology of the $Ga_2O_3$. In situ high-temperature XRD analysis revealed the crystal structure of $Ga_2O_3$ at different temperatures. The $Ga_2O_3$ obtained using the precipitation method and polymerized complex method were generally spherical-shaped particles and their average particle size was approximately 80 nm and $1{\mu}m$, respectively. The crystal structure of the $Ga_2O_3$ prepared by the precipitation method was changed from rhombohedral to monoclinic at $700^{\circ}C$, while monoclinic $Ga_2O_3$ was obtained directly from the precursor by the polymerized complex method.