Characterization of the pentacene thin-film transistors with an epoxy resin-based polymeric gate insulator

¹ LPICM, Ecole Polytechnique, CNRS, 91128 Palaiseau, France
² CEA Saclay, DSM/IRAMIS/SPCSI/LCSI, 91191 Gif-sur-Yvette, France

^a e-mail: chang-hyun.kim@polytechnique.edu

Received: 7 July 2011
Accepted: 16 November 2011
Published online: 23 December 2011

Abstract

The organic thin-film transistors (OTFTs) incorporating pentacene/SU-8 interface were fabricated and characterized. SU-8, a reliable epoxy-based photoresist, is tested as a potential highly-stable polymeric gate dielectric for OTFTs. The fabricated devices showed promising electrical performance with on-off ratio up to 10⁷ and field-effect mobility up to 0.56 cm²/V s. Several device characteristics are further analyzed. There existed a leakage current path due to the uncontrolled pentacene coverage and we revealed that precise alignment of the evaporation mask of pentacene is critical for eliminating this problem. Pentacene grain formation largely depended on the growth condition on the SU-8 surface and small-grain films offered outstanding performance possibly owing to enhanced inter-domain connections. Natural degradation of the OTFTs is also discussed in terms of environmental stability and the pentacene/SU-8 transistor operated with noticeable air stability under ambient conditions.