Study on Transfer Characteristic Hysteresis of Carbon Nanotube Thin Film Transistor

Carbon nanotube thin film transistor (CNT TFT) fabricated by solution-processed method shows hysteresis effect in the transfer characteristic test. In order to investigate the cause of hysteresis, a back-gated CNT TFT was fabricated by using a drop coating of the CNT toluene solution with a normal aromatic hydrocarbon polymer(PFO-BPy). Although there have been slight changes in the experimental materials and environmental conditions, it does not affect the test results of the electrical characteristics of carbon nanotube thin film transistors. We carried out measurement of current-voltage characteristic at various test conditions, including scanning order, scanning range, scanning speed, and vacuum environment. Moreover, device fabrication followed by surface passivation was conducted to isolate CNT network from the ambient. The results strongly suggest that, the hysteresis of solution-processed CNT TFT is generally caused by absorption of water molecules on the surface of CNT. Furthermore, surface passivation is a prospective method for suppressing hysteresis of CNT TFT made by using solution process.