• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.543-544
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• 2006

Pentacene thin film transistors fabricated without photolithographic patterning were fabricated on the plastic substrates. Both the organic/inorganic thin films and metallic electrode were patterned by shifting the position of the shadow mask which accompanies the substrate throughout the deposition process. By using an optically transparent zirconium oxide ($ZrO_2$) as a gate insulator and octadecyltrimethoxysilane (OTMS) as an organic molecule for self-assembled monolayer (SAM) to increase the adhesion between the plastic substrate and gate insulator and the mobility with surface treatment, high-performance transistor with field effect mobility $.66\;cm^2$/V s and $I_{on}/I_{off}$>$10^5$ was formed on the plastic substrate. This technique will be applicable to all structure deposited at low temperature and suitable for an easy process for flexible display.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1028-1031
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• 2009

High quality poly-SiGe thin films were prepared on 6-inch substrates using Reactive-thermal CVD with $Si_2H_6$ and $GeF_4$ around at $500^{\circ}C$ directly. Its thickness uniformity was ~ 3% on the entire substrate area. N-channel mobility of ~30 nm thick bottom-gate TFTs exceeded 20 $cm^2$/Vs without any further crystallization.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.1.1-1.1
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• 2011

Printed electronics based on the direct writing of solution processable functional materials have been of paramount interest and importance. In this talk, the synthesis of printable inorganic functional materials (conductors and semiconductors) for thin-film transistors (TFTs) and photovoltaic devices, device fabrication based on a printing technique, and specific characteristics of devices are presented. For printable conductor materials, Ag ink is designed to achieve the long-term dispersion stability and good adhesion property on a glass substrate, and Cu ink is sophisticatedly formulated to endow the oxidation stability in air and even aqueous solvent system. The both inks were successfully printed onto either polymer or glass substrate, exhibiting the superior conductivity comparable to that of bulk one. In addition, the organic thin-film transistor based on the printed metal source/drain electrode exhibits the electrical performance comparable to that of a transistor based on a vacuum deposited Au electrode. For printable amorphous oxide semiconductors (AOSs), I introduce the noble ways to resolve the critical problems, a high processing temperature above $400^{\circ}C$ and low mobility of AOSs annealed at a low temperature below $400^{\circ}C$. The dependency of TFT performances on the chemical structure of AOSs is compared and contrasted to clarify which factor should be considered to realize the low temperature annealed, high performance AOSs. For photovoltaic application, CI(G)S nanoparticle ink for solution processable high performance solar cells is presented. By overcoming the critical drawbacks of conventional solution processed CI(G)S absorber layers, the device quality dense CI(G)S layer is obtained, affording 7.3% efficiency CI(G)S photovoltaic device.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.12
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• pp.761-767
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• 1999

Poly-Si TFTs(polycrystalline silicon thin film transistors) fabricated on a low cost glass substrate have attracted a considerable amount of attention for pixel elements and peripheral driving circuits in AMLCS(active matrix liquid crystal display). In order to apply poly-Si TFTs for high resolution AMLCD, a high operating frequency and reliable circuit performances are desired. A new poly-Si TFT with CLBT(counter doped lateral body terminal) is proposed and fabricated to suppress kink effects and to improve the device stability. And this proposed device with BC(buried channel) is fabricated to increase ON-current and operating frequency. Although the troublesome LDD structure is not used in the proposed device, a low OFF-current is successfully obtained by removing the minority carrier through the CLBT. We have measured the dynamic properties of the poly-Si TFT device and its circuit. The reliability of the TFTs and their circuits after AC stress are also discussed in our paper. Our experimental results show that the BC enables the device to have high mobility and switching frequency (33MHz at $V_{DD}$ = 15 V). The minority carrier elimination of the CLBT suppresses kink effects and makes for superb dynamic reliability of the CMOS circuit. We have analyzed the mechanism in order to see why the ring oscillators do not operate by analyzing AC stressed device characteristics.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.1
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• pp.57-62
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• 1999

Polycrystaline thin film transistors are fabricated on the transparent glass substrate by a lamp-scan annealing. The line-shaped lamp scanning method, which is profitable for large area process, effectively radiated silicon film on glass substrate. Amorphous silion film absorbs the light which is emitted from halogen-lamp and it transformed into crystalline silicon by metal-induced lateral crystallization. In order to enhance the annealing effect, capping layer was deposited on the whole substrate. When the scan speed was 1-2mm/sec, lateral crystallization of amorphous silicon under capping layer was 18~27${\mu}m/scan$. The thin film transistor fabricated by this method shows high electron mobility over 130$cm^2/V{\cdot}sec$

• Journal of Sensor Science and Technology
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• v.29 no.5
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• pp.332-335
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• 2020

Drop casting, a solution process, is a simple low-cost fabrication technique that does not waste material. In this study, we elucidate the effect of the concentration of a InGaZnO solution on the electrical properties of drop-cast oxide thin-film transistors. The higher the concentration the larger the amount of remnant InGaZnO solutes, which yields a thicker thin film. Accordingly, the electrical properties were strongly dependent on the concentration. At a high concentration of 0.3 M (or higher), a large current flowed but did not lead to switching characteristics. At a concentration lower than 0.01 M, switching characteristics were observed, but the mobility was small. In addition to a high mobility, sufficient switching characteristics were obtained at a concentration of 0.1 M owing to the appropriate thickness of the semiconductor layer. This study provides a technical basis for the low-cost fabrication of switching devices capable of driving a sensor array.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.756-759
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• 2007

We have fabricated pentacene OTFT on ultra-thin flexible polyimide film with a rigid glass support. Polyimide film of the thickness of $10{\mu}m$ has formed on glass by spin coating from the solution. After the entire OTFT process, the OTFT exhibited a fieldeffect mobility of $0.4\;cm^2/Vs$, an $I_{on}/I_{off}$ ratio of $10^7$ and a subthreshold swing of 0.7 V/dec. The OTFT on polyimide film has been detached from the glass support and laminated on a plastic support of $130\;{\mu}m-thick$ PET film. After the detach process, in spite of the degrading of its field-effect mobility, the OTFT showed high $I_{on}/I_{off}$ as high $as{\sim}10^6$.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.145-148
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• 2007

The authors report on the fabrication of thin film transistors (TFTs) that use amorphous indium-gallium-zinc oxide (a-IGZO) channel and have the channel length (L) and width (W) patterned by dry etching. To prevent the plasma damage of active channel, a 100-nm-thckness $SiO_{x}$ by PECVD was adopted as an etch-stopper structure. IGZO TFT (W/L=10/50${\mu}m$) fabricated on glass exhibited the high performance mobility of $35.8\;cm^2/Vs$, a subthreshold gate voltage swing of $0.59V/dec$, and $I_{on/off}$ of $4.9{\times}10^6$. In addition, 4.1” transparent QCIF active-matrix organic light-emitting diode display were successfully fabricated, which was driven by a-IGZO TFTs.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.374-377
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• 2009

The characteristics of the deposited thin films of the zinc oxide (ZnO) at different oxygen pressures will be elucidated in this work. The resistivity of ZnO thin films were dominated by the carrier concentration under high oxygen pressure conditions while controlled by the carrier mobility at low oxygen ambiences. In addition, we will show the characteristics of the transparent ZnO based thin film transistor (TFT) fabricated at a full room temperature process with gate dielectric of gadolinium oxide ($Gd_2O_3$) thin films.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.305-308
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• 2004

We present a novel process for the ultra low temperature (<150$^{\circ}C$) polycrystalline silicon (ULTPS) TFT for the flexible display applications on the plastic substrate. The sequential lateral solidification (SLS) was used for the crystallization of the amorphous silicon film deposited by rf magnetron sputtering, resulting in high mobility polycrystalline silicon (poly-Si) film. The gate dielectric was composed of thin $SiO_2$ formed by plasma oxidation and $Al_2O_3$ deposited by plasma enhanced atomic layer deposition. The breakdown field of gate dielectric on poly-Si film showed above 6.3 MV/cm. Laser activation reduced the source/drain resistance below 200 ${\Omega}$/ㅁ for n layer and 400 ${\Omega}$/ㅁ for p layer. The fabricated ULTPS TFT shows excellent performance with mobilities of 114 $cm^2$/Vs (nMOS) and 42 $cm^2$/Vs (pMOS), on/off current ratios of 4.20${\times}10^6$ (nMOS) and 5.7${\times}10^5$ (PMOS).