Homochiral carbon nanotube van der Waals crystals.

For applications of single-walled carbon nanotubes (SWNTs) in integrated circuits, it is crucial to have high-tube density arrays of SWNTs that are well aligned and purely semiconducting. In this work, we report on the direct growth of close-packed SWNT arrays on hexagonal boron nitride (hBN) substrates, demonstrating high alignment and uniform chirality within each array. Molecular dynamics simulations suggest that a self-assembly growth mechanism resulted from the intertube van der Waals attraction and the ultralow sliding friction of SWNTs on the atomically flat hBN substrate. Field-effect transistors constructed from the grown SWNT array exhibit high performance at room temperature, with mobilities of up to 2000 square centimeters per volt per second, on/off ratios of ~107, and a maximum current density of ~6 milliamperes per micrometer.