A carbon nanotube–graphene nanoribbon seamless junction transistor†
The nature and type of intramolecular junctions are very important for nanoelectronics. Here, a new way of fabricating seamless junctions between carbon nanotubes and graphene nanoribbons (GNRs) is demonstrated. Dielectrophoretically aligned multi-walled carbon nanotubes (CNTs) across metal electrodes are etched with an Ar ion beam at low pressure. We show that grounding of metal electrodes plays an important role in the etching of CNTs in contact with the metal electrodes. If electrodes are grounded, that portion of the CNT doesn't get etched due to the discharge of ions through the ground, and CNT to GNR conversion occurs in the gap region between the metal electrodes. Thus produced GNRs have a large aspect ratio of ∼90, and Raman spectroscopy analysis shows that the distance between the defects is ∼65 nm. The CNT–GNR–CNT seamless junctions are ohmic in nature and the transistor shows a current on/off ratio of 27 with a hole mobility of 350 cm2 V−1 s−1.