• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.4
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• pp.357-361
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• 2006

The electrical performances of organic thin-film transistors (OTFTs) have been improved for the last decade. In this paper, it was demonstrated that the electrical characteristics of the organic thin film transistors (OTFTs) were improved by using polymeric material as adhesion layer on gate insulator. We have investigated OTFTs with polyimide adhesion layer which was fabricated by vapor deposition polymerization (VDP) processing and formed by co-deposition of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride and 4,4'-oxydianiline. It was found that the OTFTs with adhesion layer showed better electrical characteristics than with bare layer because of good matching between semiconductor and gate insulator. Our devices of performance are field effect mobility of $0.4cm^2/Vs$, threshold voltage of -0.8 V and on-off current ratio of $10^6$. In addition, to improve the electrical characteristics of OTFT, we have reduced the thickness of adhesion layer up to a few nanometrs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.70-71
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• 2005

The electrical performances of organic thin-film transistors (OTFTs) have been improved for the last decade. In this paper, it was demonstrated that the electrical characteristics of the organic thin film transistors (OTFTs) were improved by using polymeric material as adhesion layer on gate insulator. We have investigated OTFTs with polyimide adhesion layer which was fabricated by vapor deposition polymerization (VDP) processing and formed by co-deposition of 6FDA and ODA. It was found that the OTFTs with adhesion layer showed better electrical characteristics than with bare layer because of good matching between semiconductor and gate insulator. Our devices of performance are field effect mobility of $0.4cm^2$/Vs, threshold voltage of -0.8 V and on-of current ratio of $10^6$. In addition, to improve the electrical characteristics of OTFT, we have reduced the thickness of adhesion layer up to a few nanometrs.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.4 s.37
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• pp.359-363
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• 2005

The organic insulation devices with MIM (metal-insulator-metal) structures as PVP gate insulation films were prepared for the application of organic thin film transistors (OTFT). The co-polymer organic insulation films were synthesized by using PVP(poly-4-vinylphenol) as solute and PGMEA (propylene glycol monomethyl ether acetate) as solvent. The cross-linked PVP insulation films were also prepared by addition of poly (melamine-co-formaldehyde) as thermal hardener. The leakage current of the cross-linked PVP films was found to be about 300 pA with low current noise. and showed better property in electrical properties as compared with the co-polymer PVP insulation films. In addition, cross-linked PVP insulation films showed better surface morphology (roughness), showing about 0.11${\~}$0.18 nF in capacitance for all PVP film samples.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.12
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• pp.1009-1013
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• 2009

In this study, we have been synthesized the dielectric layer using pure organic and organic-inorganic hybrid precursor on flexible substrate for improving of the organic thin film transistors (OTFTs) and, design and fabrication of organic thin-film transistors (OTFTs) using small-molecule organic semiconductors with pentacene as the active layer with record device performance. In this work OTFT test structures fabricated on polymerized substrates were utilized to provide a convenient substrate, gate contact, and gate insulator for the processing and characterization of organic materials and their transistors. By an adhesion development between gate metal and PI substrate, a PI film was treated using $O_2$ and $N_2$ gas. The best peel strength of PI film is 109.07 gf/mm. Also, we have studied the electric characteristics of pentacene field-effect transistors with the polymer gate-dielectrics such as cyclohexane and hybrid (cyclohexane+TEOS). The transistors with cyclohexane gate-dielectric has higher field-effect mobility, $\mu_{FET}=0.84\;cm^2/v_s$, and smaller threshold voltage, $V_T=-6.8\;V$, compared with the transistor with hybrid gate-dielectric.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.566-567
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• 2009

We have examined the silicon nitride ($SiN_x$) as gate insulator with the ammonia ($NH_3$) plamsa treatment for the soluble derivatives of polythiophene as p-type channel materials of organic thin film transistors (OTFTs). Fabrications of the jetting-processed OTFTs with $SiN_x$ as gate insulator by $NH_3$ plasma treatment can be similar to performance of OTFTs with silicon dioxide ($SiO_2$) insulator.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.12
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• pp.1063-1066
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• 2009

In this study, we fabricated pentacene organic thin film trasistors(OTFTs) which used aluminum oxide as the gate insulator. Aluminum oxide for OTFTs was deposited on glass substrate with a different deposition rate by E-beam evaporation. In case of the deposition rate of $0.1\;{\AA}$, the fabricated aluminum oxide gate insulating OTFT showed a threshold voltage of -1.36 V, an on/off current ratio of $1.9{\times}10^3$ and field effect mobility $0.023\;cm^2/V_s$.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1295-1297
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• 2007

In this study, we report that the characteristics of OTFTs can be improved by the UV exposure of the surface of the synthesized photo-reactive gate insulator, and be optimized by controlling the exposure time. As a gate dielectric, the modified PVP was prepared by substituting hydroxyl group in PVP with cinnamoyl group. The synthesis details and the effects of the modified PVP on the device performance are discussed.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.276-279
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• 2008

Air stable n-type organic field effect transistors (OFETs) based on CB60B are realized using a perfluoropolymer as the gate dielectric layer. The devices showed the field-effect mobility of $0.05\;cm^2P/V\;s$ in ambient air. Replacing the gate dielectric material by $SiO_2$ resulted in no transistor action in ambient air. Perfluorinated gate dielectric layer reduces interface traps significantly for the n-type semiconductor even in ambient air.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.777-779
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• 2002

We report the performance of pentacene-based organic thin film transistors (OTFT) with PMMA (polymethyl methacrylate) as the gate insulator which was spin-coated on the ITO (indium tin oxide) glass substrate which was used as the gate contact. The pentacene thin film was deposited on the PMMA film and then Au source/drain contacts were deposited through shadow mask. The pentacene film shows better molecular ordering on PMMA compared with $SiO_2$ of Si wafer. The devices exhibited the field effect mobility of ${\sim}0.004cm^2$/Vs and on/off current ratio of ${\sim}10^3$.

• 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.