AVS 53rd International Symposium
    Electronic Materials and Processing Thursday Sessions
       Session EM-ThM

Paper EM-ThM1
Organic Thin Film Transistors with an Organic/High-k Inorganic Bilayer Gate Dielectric Layer

Thursday, November 16, 2006, 8:00 am, Room 2001

Session: Organic Electronic Materials and Devices
Presenter: Y.G. Seol, Sungkyunkwan University, Korea
Authors: Y.G. Seol, Sungkyunkwan University, Korea
S.S. Lee, Hanyang University, Korea
J.H. Lee, Hanyang University, Korea
N.-E. Lee, Sungkyunkwan University, Korea
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To develop the high performance OTFT devices, low threshold voltage (V@sub T@), low-leakage current, high current on-off ratio, and channel mobility are needed. To achieve low V@sub T@ and low-leakage current level, use of thin high-k gate dielectrics is required. For this purpose, the organic/inorganic (high-k) bilayer gate dielectric layers were investigated in this work. Flexible organic thin film transistors were fabricated using pentacene as a semiconducting layer and electroplated nickel (Ni) as a gate electrode on polyimide substrate. Electroplated gate electrode formed on the plasma-treated polyimide substrate provides a good adhesion. First, poly(4-vinyl phenol) (PVP) as an organic gate dielectric layer was deposited by spin coating after Ni gate electrode formation. Ultra-thin (10 nm) HfO@sub 2@ as a high-k dielectric deposited by ALD (atomic layer deposition) on the spin-coated PVP layer. ALD of HfO@sub 2@ layer was carried out at the substrate temperature 220 ~ 240°C. Pentacene as a semiconductor layer was thermally evaporated on the gate dielectric layer using a shadow mask in vacuum chamber at the substrate temperature of 80°C and then the thermal evaporation of gold source and drain electrodes was followed. The OTFT devices with no ALD HfO@sub 2@ layer were also fabricated for comparison. The channel length varied from 10 to 110µm, and the channel width was 800µm. The measured I-V characteristics indicated the significant reduction in the leakage current for thinner PVP layer and improvement of current on-off ratio.