Lateral plasma etching enhanced on/off ratio in graphene nanoribbon field-effect transistor

Opening the transport gap in graphene by minimizing its width is highly desirable to achieve outstanding switching performance, i.e., the high on/off ratio, in its field effect transistors (FETs). In this letter, we propose a simple method to open a comparable transport gap in graphene by narrowing down it into graphene nanoribbon (GNR) via the conventional nanofabrication procedure. In the process, GNR capped with a 50-nm-wide hydrogen-silsesquioxane mask is trimmed down from the edges by lateral plasma etching. The on/off ratio of the FET device is dramatically enhanced by two orders of magnitude as etching duration increases. The large on/off ratios of ∼47 and ∼105 are achieved at room temperature and 5.4 K, respectively. The electrical measurement reveals a transport gap opening of ∼145 meV in GNR, which corresponds to a resulting width of