Gate Dielectric Effects on Ambipolar Transport in Polymer-Wrapped Single-Walled Carbon Nanotube Network Transistors

This study examines the effects of polymer gate dielectric layers on the charge transport properties of both holes and electrons in solution-processed polymer-wrapped single-walled carbon nanotube (s-SWCNT) network transistors. The dielectric constant plays a crucial role in determining charge transport characteristics, leading to a transition from hole-dominated to electron-dominated ambipolarity as it increases. To elucidate the underlying mechanisms, we analyze the contact resistance (Rc), effective trap state density (Neff), and mobility in relation to the induced charge density (Qind). Our findings indicate that high-k polymer dielectrics exhibit two distinct effects: their randomly aligned dipoles induce energetic disorder at the s-SWCNT network interface, while their high capacitance reduces Rc and Neff. Hole transport is primarily affected by energetic disorder, whereas electron transport is influenced by reduced Rc and Neff. This difference arises due to variations in the Schottky–Mott limit between the gold source/drain electrodes and the conduction and valence bands.