Transistors fabricated using the single crystals of [8]phenacene

Abstract

Field-effect transistors (FETs) with single crystals of a new phenacene-type molecule, [8]phenacene, were fabricated and characterized. This new molecule consists of a phenacene core of eight benzene rings, with an extended π-conjugated system, which was recently synthesized for use in an FET by our group. The FET characteristics of an [8]phenacene single-crystal FET with SiO₂ gate dielectrics show typical p-channel properties with an average field-effect mobility, 〈μ〉, as high as 3(2) cm² V⁻¹ s⁻¹ in two-terminal measurement mode, which is a relatively high value for a p-channel single-crystal FET. The 〈μ〉 was determined to be 6(2) cm² V⁻¹ s⁻¹ in four-terminal measurement mode. Low-voltage operation was achieved with PbZr_0.52Ti_0.48O₃ (PZT) as the gate dielectric, and an electric-double-layer (EDL) capacitor. The 〈μ〉 and average values of absolute threshold voltage, 〈|V_th|〉, were 1.6(4) cm² V⁻¹ s⁻¹ and 5(1) V, respectively, for PZT, and 4(2) × 10⁻¹ cm² V⁻¹ s⁻¹ and 2.38(4) V, respectively, for the EDL capacitor; these values were evaluated in two-terminal measurement mode. The inverter circuit was fabricated using [8]phenacene and N,N′-1H,1H-perfluorobutyldicyanoperylene-carboxydi-imide single-crystal FETs. This is the first logic gate circuit using phenacene molecules. Furthermore, the relationship between μ and the number of benzene rings was clarified based on this study and the previous studies on phenacene single-crystal FETs.