Electrical properties and memory effects of field-effect transistors from networks of single and double-walled carbon-nanotubes*

We study field-effect transistors made of single and double-walled carbon nanotube networks for applications as memory devices. The transfer characteristics of the transistors exhibit a reproducible hysteresis which enables their use as nano-sized memory cells with operations faster than 10 ms, endurance longer than 10$^{+4}$ cycles and charge retention of few hours in air. We propose water enhanced charge trapping at the SiO$_{2}$/air interface as the dominant mechanism for charge storage. We show that charge storage can be improved by limiting device exposure to air.