Control of Schottky barrier height for efficient fabrication of graphene nanoribbon-based quantum dot devices

Recently, we demonstrated the fabrication of graphene nanoribbon (GNR)-based quantum dot devices by advanced plasma CVD with one-dimensional Ni nanobar as a catalyst [1-2]. Detailed measurements at cryogenic temperatures using liquid helium revealed the formation of a fine structure in the centre of the GNRs, which has the characteristics of quantum dots. However, the use of a confinement barrier naturally formed within GNR made its reproduction difficult. In this study, the confinement barrier height of the device was actively controlled by introducing two-step electron-beam lithography, which can change the kinds of nanobar and electrode metal. Detailed measurements revealed that the Schottky barrier height between the electrodes and GNRs was varied by changing the metal species used for the electrodes. This suggests that the Schottky barrier height control between the electrodes and GNR may useful to increase the fabrication yield of GNR-based quantum dot devices.