▎ 摘　　要

We present numerical simulations of high field transport in both suspended and deposited armchair graphene nanoribbon (A-GNR) on HfO2 substrate. Drift velocity in suspended GNR does not saturate at high electric field (F), but rather decreases, showing a maximum for F approximate to 10 kV/cm. Deposition on HfO2 strongly degrades the drift velocity by up to a factor approximate to 10 with respect to suspended GNRs in the low-field regime, whereas at high fields, drift velocity approaches the intrinsic value expected in suspended GNRs. Even in the assumption of perfect edges, the obtained mobility is far behind what expected in two-dimensional graphene, and is further reduced by surface optical phonons. (C) 2011 American Institute of Physics. [doi:10.1063/1.3664091]