Enhancement of ambipolar characteristics in single-walled carbon nanotubes using C60 and fabrication of logic gates

We demonstrate a technique to convert p-type single-walled carbon nanotube (SWNT) network transistor into ambipolar transistor by thermally evaporating C60 on top. The addition of C60 was observed to have two effects in enhancing ambipolar characteristics. First, C60 served as an encapsulating layer that enhanced the ambipolar characteristics of SWNTs. Second, C60 itself served as an electron transporting layer that contributed to the n-type conduction. Such a dual effect enables effective conversion of p-type into ambipolar characteristics. We have fabricated inverters using our SWNT/C60 ambipolar transistors with gain as high as 24, along with adaptive NAND and NOR logic gates.