Patterned Carbon Nanotube Thin-Film Transistors with Transfer-Print Assembly

Conditions for the transfer printing of patterned carbon nanotube (CNT) films, along with a Au-gate, a poly methylmethacrylate (PMMA) dielectric layer and Au source-drain electrodes have been developed for the fabrication of thin-film transistors on a polyethylene terephthalate (PET) substrate. Chemical vapor deposition (CVD) grown CNTs were patterned using a photolithographic method. Transfer printing was used to fabricate devices having both top gate and bottom gate configurations. Replacement of the SiO2 dielectric with PMMA correlates with a decreased hysteresis in the transconductance behavior. Encapsulation of the CNTs between the polymeric substrate and dielectric layer yields ambipolar behavior. Variations in device performance are also observed as a function of CNT film density and channel length, suggesting changing contributions of the metallic and semiconducting CNTs to the transport mechanism.