| AVS 58th Annual International Symposium and Exhibition | |
| Graphene and Related Materials Focus Topic | Thursday Sessions |
| Session GR+TF+NS-ThA |
| Session: | Graphene Nanoribbons and Related Structures |
| Presenter: | Zhixian Zhou, Wayne State University |
| Authors: | M.-W. Lin, Wayne State University C. Ling, Wayne State University L.A. Agapito, California State University Northridge N. Kioussis, California State University Northridge Y. Zhang, Wayne State University M.-C. Cheng, Wayne State University W.L. Wang, Harvard University E. Kaxiras, Harvard University Z.X. Zhou, Wayne State University |
| Correspondent: | Click to Email |
We report the first variable-temperature electrical-transport study of suspended ultra-low-disorder GNRs with nearly atomically smooth edges. Suspension of the GNRs not only removes the substrate influence but also allows a thorough removal of impurities, including those trapped at the interface between the GNR and the substrate, leading to a substantial increase of the carrier mobility. We observe high mobility values over 3000 cm2 V-1 s-1 in GNRs that are ~ 20 nm wide, the highest reported to date on GNRs of similar dimensions. Furthermore, we demonstrate that the activation gap extracted from the simple activation behavior of the minimum conductance and residual carrier density at the charge neutrality point approaches the intrinsic bandgap in ultra-low-disorder GNRs. Comparison of the bandgap values of multiple samples shows that the bandgap in our ultra-low-disorder samples is approximately inversely proportional to the ribbon width, consistent with theoretical predictions. On the other hand, non-negligible disorder in GNRs obscures the observation of the intrinsic bandgap in transport measurements. In addition, the size of the bandgap derived from the transport measurements is in quantitative agreement with the results of our complementary tight-binding calculations for a wide range of chiral angles characterizing the GNR structure, suggesting that the underlying electronic origin of bandgap enhancement is the magnetism of the zigzag edges.