▎ 摘　　要

The high intrinsic carrier mobility of graphene has drawn much attention. However, the high contact resistance between the graphene and metal electrode limits the application of high-speed graphenebased transistors. In this work, we combined both electrical characterization and Raman spectroscopy to study the contact resistance issue in graphene field effect transistor (FET). As FET size scaling down, the graphene-metal contact resistance is found to be a significant contributor to the total resistance. The signature of the graphene/metal bonding with various metal electrodes is probed by using highresolution Raman spectroscopy. Graphene-metal Raman signals vary on different metal electrodes. This study unearths the properties of the graphene/metal bonding, and paves away for the investigations into improving the stability and scalability of the graphene-based transistor for future high-speed nanoelectronics. (C) 2017 Elsevier Ltd. All rights reserved.