High-field-effect-mobility pentacene thin-film transistors with polymethylmetacrylate buffer layer

A thin film of polymethylmetacrylate (PMMA) acting as a buffer layer has been employed in order to fabricate high-quality pentacene thin-film transistors (TFTs), both in bottom contact and top contact configuration. A PMMA buffer layer allows to reduce the interaction between a pi-conjugated system of pentacene and the metal or dielectric substrate. We show that a thin PMMA buffer layer improves crystal quality along the metal contacts' boundaries, while still allowing good ohmic contact. Pentacene TFTs, including a PMMA buffer layer, show very high field-effect mobility, mu(FE)=0.65 and 1.4 cm(2)/V s, for bottom and top contact configuration, respectively, and remarkable steep subthreshold region. (c) 2005 American Institute of Physics.