High-Temperature Operation of Pentacene Field-Effect Transistors with Polyimide Gate Insulators
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I1.9.1
High-Temperature Operation of Pentacene Field-Effect Transistors with Polyimide Gate Insulators
Tsuyoshi Sekitani, Shingo Iba, Yusaku Kato, Yoshiaki Noguchi, and Takao Someya Quantum-Phase Electronics Center, School of Engineering, the University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
Takayasu Sakurai Center for Collaborative Research, the University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
We have fabricated pentacene field-effect transistors (FETs) on polyimide-sheet films with polyimide gate dielectric layers and parylene encapsulation layer, and investigated the high-temperature performance. It is found that the mobility of encapsulated FETs is enhanced from 0.5 to 0.8 cm2/Vs when the device is heated from room temperature to 160 ºC under light-shielding nitrogen environment. Furthermore, after the removal of annealing temperatures up to 160 ºC, the transistor characteristic of mobility and on/off current ratio show no significant changes, demonstration the excellent thermal stability of the present organic FETs.
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Correspondence should be sent to [email protected]
I1.9.2
There has been an increase of research on organic field-effect transistors (FETs) to realize new concepts of electric devices in the next generation, such as flexible, lightweight, printable, and large-area. Recently, electric circuits consisting of organic transistors have been successfully manufactured as applications for driving devices for paper-like displays [1,2], radio-frequency identification-tags [3,4], and large-area sensors [5,6]. Great progresses have been performed on organic transistors, while one of the concerns for organic transistors might be stability at high temperatures because a lot of organic materials have low heat resistance. For example, plastic films often show shrinkage and flexure after the removal of annealing temperatures, which are understood as associated with low melting point and large thermal expansion coefficient of organic materials [7]. Such high-temperature degradations must result in the destruction of organic devices although organic FETs are expected as one of the convenient devices that can be utilized at wide range of applications.
In this work, we have manufactured pentacene FETs on polyimide films with polyimide gate dielectric layers, which are encapsulated by passivation layers, and have successfully suppressed high-temperature-induced degradations of transistor performance. Although the mobility of non-encapsulated FETs is increased by more than twice when the devices are heated from room temperature to 160 ºC, parylene encapsulation on organic FETs suppress the significant changes of mobility even at high temperatures up to 160 ºC. Furthermore, we also measure the transistor characteristics at room temperature after the removal of annealing temperatures in order to investigate the postannealing effect. The encapsulated FETs show no significant changes after annealing up to 160 ºC.
I1.9.3
Pentacene FETs have been fabricated on plastic
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