Characteristics of tetracene-based field-effect transistors on pretreated surfaces

Tetracene-based organic thin-film transistors (OTFTs) were prepared using a neutral cluster beam deposition (NCBD) method. The effect of surface modification with an amphiphilic surfactant, octadecyltrichlorosilane (OTS), on the formation of thin films and the geometric influence of channel length and width on the transistor characteristics were systematically examined. The estimated trap density and temperature-dependence of the field-effect mobility in the range of 10-300 K demonstrated that surfactant pretreatment decreased the total trap density and activation energy for hole-transport by reducing structural disorder in the active layer. In particular, the room-temperature hole mobilities of 0.162 and 0.252 cm²/Vs for untreated and OTS-pretreated devices were among the best to date for polycrystalline tetracene-based transistors using SiO₂ gate dielectric layers without any thermal post-treatment.