This paper presents new results on miniaturized pentacene thin film transistors (TFTs) fabricated on a spin coated polyimide (PI) film. Patterning steps, which are vital for the integrity and electrical performance of organic TFTs, were done using resistless shadow-mask lithography with two high precision MEMS fabricated stencils, thus avoiding solvents and high temperature processes. Both pentacene and source-drain (S/D) electrodes were directly patterned through stencils with high accuracy on wafer scale. The TFTs have been characterized before and after peeling the flexible PI film off the rigid surface, showing full transistor functionality in both cases.

a b s t r a c tIn this work double-gate pentacene TFT architecture is proposed and experimentally investigated. The devices are fabricated on a polyimide substrate based on a process that combines three levels of stencil lithography with standard photolithography. Similarly to the operation of a conventional double-gate silicon FET, the top-gate bias modulates the threshold voltage of the bottom-gate transistor and significantly improves the transistor sub-threshold swing and leakage current. Moreover, the double gate TFT shows good promise for the enhancement of I ON /I OFF , especially by the control of I OFF in devices with poor top interfaces.

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a b s t r a c tIn this work a high-k double-gate pentacene field-effect transistor architecture is presented. The devices are fabricated on a flexible polyimide substrate by three aligned levels of stencil lithography combined with standard photolithography. ALD-deposited high-k HfO 2 and parylene D device passivation, together with Pt top-gate deposition provide very good electrostatic control of the channel, showing low leakage current and improved subthreshold. The ION/IOFF ratio is of the order of 10 6 and the IOFF lower than 0.1 pA/lm. We also report a comparison of the normal, FET-like (VD < 0) and reverse, diode-like (VD > 0) modes of the p-OFET. We find a higher current drive in the reverse diode-like mode compared to normal FET-like mode. The reverse mode has clearly defined OFF and ON states versus the drain voltage and non-saturated output characteristics, which makes it suitable for the use in RF and analog applications of OFETs.