Selective metallization and passivation of dry-transferred carbon nanotubes in field-effect transistors

Abstract

The use of selective atomic layer deposition (ALD) of platinum and alumina was investigated for top-clamping and passivation of contacts of suspended pristine single-walled carbon nanotubes (SWNTs). This wet-chemical-free process offers an interesting alternative to lithography-based methods as it avoids degradation of the transfer characteristics by resist residues or amorphous carbon deposition on the carbon nanotubes (CNTs) in field-effect transistor (FET) configuration. It was observed that the annealing and clamping effect can be used not only to obtain lower contact resistances and higher signal to noise ratio (SNR), but also to induce, what appears to be, band gap opening in metallic nanotubes. On average, a current increase of more than one order of magnitude and SNRs as high as 200 could be observed for metallized and passivated small-gap semiconducting CNTs.