Fabrication and characterisation of high-performance and high-current back-gate thin-film field-effect transistors using sorted single-walled carbon nanotubes

The authors present the wafer scale fabrication and characteristics of back-gate semiconducting carbon nanotube thin-film field-effect transistors (SN-TFTs) suitable for high-current applications. Good on-off current ratio TFTs using affordable 95- purity semiconducting tubes by appropriately choosing the length of the nanotubes and improving the nanotube density have been demonstrated. Moreover, the nanotube thin-film deposition is carried out using a simple solution-based assembly method and good TFT performance and high currents are achieved with random-oriented network of nanotubes. Hafnium oxide (HfOx) is used as the gate dielectric material to improve the device performance. The global gate devices have shown an excellent p-type behaviour with a low output conductance value of 0.3 S. The SN-TFTs have exhibited a maximum on off ratio of 4 10⁴ at lower operating gate voltages, a maximum on-current of 3.1 mA at a current density of 6.2 A/ m, a steep sub-threshold slope of 600 mV/decade, threshold voltage of 1.5 V, a maximum normalised transconductance of 0.7 S/ m and a maximum carrier mobility of 44.2 cm²/V s.