Investigating electrical properties of controllable graphene nanoribbon field effect transistors

Abstract

It is always an important issue to open the energy gap for graphene while retaining its high carrier mobility. Narrowing down large-area graphene into graphene nanoribbons (GNRs) is one of the ways to open the energy gap to achieve field-effect transistors (FET) suitable for logic circuits. But it has been a problem to obtain GNRs with controllable width and specific boundary structure. In this work, we proposed a simple high-precision preparation method for GNRs. In the process, GNRs with a width of 200 nm and smooth edges were prepared by a focused ion beam (FIB) etching process. Graphene nanoribbon field-effect transistors (GNR-FET) were fabricated by electron beam lithography (EBL). In this device, due to the proximity of the edge of the He+ during the FIB etching process, the carbon atom structure of the GNRs edge was changed, resulting in variations in electron transport properties. The electrical performance test demonstrated that the on/off current ratio of the GNR-FET device was up to 103 at room temperature. The structural defects of the GNRs caused the device carrier mobility down to 371.6 cm2V−1s−1. The structural defects in the GNRs edge introduced by FIB can improve the on/off current ratio of the device and hence enhanced its electrical regulation performance. Our work provides a simple method of making controllable GNRs to fabricate field effect transistors.