Architecture Effects for Transfer-Printed Carbon Nanotube Mat Transistors

Transfer printing methods have been developed to assemble both top gate -- top source/drain and bottom gate -- bottom source/drain carbon nanotube (CNT) thin-film transistors (TFT) onto flexible substrates. The devices consist of CNT mats as the semiconductor layer, a poly(methyl methacrylate) dielectric layer and gold electrodes on a polyethylene terephthalate substrate. As a function of gate voltage (V$_{G})$, the top gate -- top source/drain devices exhibit ambipolar behavior with no hysteresis$^{\ast }$. This is in contrast to bottom gate -- top source/drain CNT mat TFTs with a SiO$_{2}$ dielectric layer which show only p-type characteristics and a large hysteresis. Fabrication and characterization of both CNT TFT architectures fabricated on flexible substrates via transfer printing will be presented and discussed. $^{\ast }$ D. R. Hines et al., Appl. Phys. Lett. 86, 163101 (2005).