▎ 摘　　要

We have performed nonequilibrium Green function simulations on the transport characteristics in ultra-small graphene nanoribbon resonant-tunneling transistors (RTTs). For an ultra-narrow nanoribbon transistor, the current-voltage characteristics resemble those observed in large-size graphene-based RTTs. For a wider nanoribbon transistor, we find that two types of structure due to inter-subband transitions appear in addition to the main peak: one originates from the resonance at k(x) = 0, while the other is due to resonance at finite k(x). (C) 2014 The Japan Society of Applied Physics