Carbon nanotube thin film transistor devices

In this study, it was demonstrated that full semiconductor device yield can be achieved using SWNT solutions prepared by selective functionalization of SWNTs with diazonium reagents and followed by density gradient ultracentrifugation (DGU) to remove most of M species and impurities. By increasing the network thickness, the effective mobility of the devices can be raised to ~10 cm2/V⋅s while keeping the on-off ratio higher than 5000. According to the positive relationship between effective mobility and network thickness, it is possible to tune the mobility of solution processed SWNT transistors by controlling the thickness of SWNT films. The removal of impurities is found to be essential for achieving high on-off ratio devices. Instead, removal of M species is crucial to obtain good on-off characteristics. It is speculated that the achievement of the full semiconductor device yield using the SWNTs consisting of small diameter tubes is due to the significant differences between chiralities in terms of the reactivity with diazonium salts.