Nitrogen-Doped Graphene Synthesized from a Single Liquid Precursor for a Field Effect Transistor

Opening the band gap of graphene is among the most important issues in modulating its electrical properties for electronic device applications. In this study, we report on the synthesis of nitrogen-doped graphene for field effect transistors. The graphene doped with nitrogen was synthesized by thermal chemical vapor deposition using a single liquid precursor of dimethylformamide, which contains both carbon and nitrogen sources. Material characterization by Raman spectroscopy, high-resolution transmission electron microscopy, and x-ray photoelectron spectroscopy confirmed the successful synthesis of high-quality nitrogen-doped graphene with a thickness of two or three atomic layers. By simply using dimethylformamide as a liquid precursor, we could dope N into graphene with a doping level of 0.64 at.%. The synthesized graphene was used to fabricate a field effect transistor, the characteristics of which were systematically studied at different temperatures (15–105°C) in air and in a vacuum. Results showed that the synthesized graphene exhibits p-type behavior in air but n-type behavior in a vacuum with a band gap of about 0.03 eV. The field effect mobility calculated at room temperature was 359 cm2 V−1 s−1. The fabricated field effect transistor has potential applications in electronic devices.