Rhodium (Rh) is found similar to Palladium (Pd) in making near-ohmic electrical contacts to single-walled carbon nanotubes (SWNTs) with diameters d > ~ 1.6 nm. Non-negligible positive Schottky barriers (SBs) exist between Rh or Pd and semiconducting SWNTs (S-SWNTs) with d < ~ 1.6 nm. With Rh and Pd contacts, the characteristics of SWNT field-effect transistors (FETs) and SB heights at the contacts are largely predictable based on the SWNT diameters, without random variations among devices. Surprisingly, electrical contacts to metallic SWNTs (M-SWNTs) also appear to be diameter dependent especially for small SWNTs. Ohmic contacts are difficult for M-SWNTs with diameters < ~ 1.0 nm possibly due to tunnel barriers.
@article{arxiv.cond-mat/0505431,
title = {Electrical Contacts to Carbon Nanotubes Down to 1nm in Diameter},
author = {Woong Kim and Ali Javey and Ryan Tu and Jien Cao and Qian Wang and Hongjie Dai},
journal= {arXiv preprint arXiv:cond-mat/0505431},
year = {2015}
}