Polyfluorene-Sorted, Carbon Nanotube Array Field-Effect Transistors with Increased Current Density and High On/Off Ratio

Challenges in eliminating metallic from semiconducting single-walled carbon nanotubes (SWCNTs) and in controlling their alignment have limited the development of high-performance SWCNT-based field-effect transistors (FETs). We recently pioneered an approach for depositing aligned arrays of ultra-high-purity semiconducting SWCNTs, isolated using polyfluorene derivatives, called dose-controlled floating evaporative self-assembly. Here, we tailor FETs fabricated from these arrays to achieve on-conductance (G(on)) per width and an onoff ratio (Gon/Goff) of 261 mu S/mu m and 2 x 10(5), respectively, for a channel length (L-ch) of 240 nm and 116 mu S/mu m and 1 x 10(6), respectively, for an L-ch of 1 mu m. We demonstrate 1400x greater G(on)/G(off) than SWCNT FETs fabricated by other methods, at comparable Gon per width of similar to 250 mu S/mu m and 30100x greater Gon per width at comparable G(on)/G(off) of 10(5)-10(7). The average Gon per tube reaches 5.7 +/- 1.4 mu S at a packing density of 35 tubes/mu m for Lch in the range 160-240 nm, limited by contact resistance. These gains highlight the promise of using ultra-high-purity semiconducting SWCNTs with controlled alignment for next-generation semiconductor electronics.