▎ 摘　　要

Local density of state (LDOS), current-voltage characteristic (I-V characteristic) and differential conductance (DC) Of pure and defected zigzag and armchair graphene nanoribbons quantum dots (GNRQDs) are investigated. We found that for the pure systems of armchair GNRQDs, the DC has oscillation feature where these oscillations could be explained by I D characteristic of atomic wires. In our samples, these wires constructed from sites with the same symmetry along the GNRQD length. Some of these wires have metallic features while some of them show semiconducting features. The zigzag GNRQDs have approximately ohmic behavior. Also it is found that the defected DC significantly depend on vacancy position. (C) 2009 Elsevier B.V. All rights reserved.