All-Semiconducting nanotube networks Thin Film Transistors: An insight towards High Performance Printed Nanoelectronics

In this work, we present our progress towards devices fabrication using all semiconducting nanotubes as the starting material. A critical issue is the ink formulation and dependence of electronic properties on the nanotube density after deposition. These are some of the first spin-on, all semiconducting nanotube devices ever made and initial results are quite promising for printed RF electronics. Semiconducting single-walled nanotube (99{\%}) ink was used to deposit nanotube network on APTES modified Si/SiO$_{2}$ substrate. Following the nanotube deposition, source and drain electrodes (Pd/Au) were deposited using standard photolithography and E-beam evaporation. The Si wafer was used for back gating and SiO$_{2}$ as the gate dielectric. The impact of density of nanotube was studied for 3 random densities. We also studied the effect of gate length on mobility, and on/off ratio, for devices with different gate lengths (10$\sim $100 $\mu $m). DC characterization of devices shows a high mobility, up to 40 cm$^{2}$/V-s, and good on/off ratio up to the order of 10$^{4}$ in some cases. Since we are using 99{\%} semiconducting ink, a high on/off ratio is expected, which is true in our devices. The on/off ratio of more than 1000 and mobilities up to $\sim $40 cm$^{2}$/V-s were observed in almost all devices.