Doping Effect Investigation of Conjugated Polymer Wrapped Single-Walled Carbon Nanotube (SWNT) for CNT Field Effect Transistors (CNTFETs) Carrier Type Tuning

Abstract

Solution-processed active semiconductor doping would be a powerful strategy in order to improve CNTFETs performance in balanced charge transport. CNTs are promising material for high performance, large area printable and flexible thin film transistor. However, as synthesized single-walled carbon nanotubes (SWNTs) show non-uniform electrical properties due to the mixture of metallic and semiconducting SWNTs. Selective separation of semiconducting SWNTs (s-SWNTs) using conjugated polymers has been developed with the aim of utilizing their superior properties. We separated s-SWNTs with the high purity from as-grown mixed-type SWNTs using conjugated polymer with long alkyl sidechain length. Separated s-SWNTs were adapted for active layer of CNTFETs with or without dopant. Properties and doping effects of the CNTFETs active layer were revealed by UV-VIS spectroscopy, Raman Spectroscopy, low-temperature measurements and other experiments. We demonstrate that hole and electron charge carrier tuning can be easily achieved by simple spin coating in CNTFETs with s-SWNT/dopant bilayer structure. Furthermore, through this study, we implemented logic gates such as inverter and pass gate with simple solution processing