Growth and electrical properties of n-type monolayer sulfur-doped graphene film in air

Abstract Theoretical calculations demonstrate that sulfur doping is a promising n-type doping method to modulate the electrical properties of graphene. However, as far as we know, the reported sulfur-doped graphene (SG) films have all shown the p-type behavior in air, where doped sulfur atoms have been mainly in the form of thiophene-like S‒C structures. The reason is that thiophene-like S‒C structures as donors cannot fully neutralize the effect of adsorbed oxygen/water molecules as acceptors on the SG film. In this study, the monolayer SG film has been synthesized by the chemical vapor deposition method, where the doped sulfur atoms are mainly in the form of S‒H structures. The electrical studies reveal that the electron concentration of SG film is ~1.1 × 1012 cm−2, indicating the typical n-type behavior in air; moreover, its mobility is as high as ~753 cm2 V−1 s−1, which is obviously higher than those of reported SG films. To the best of our knowledge, it is the first time to obtain the n-type SG film in air. The good performance of n-type SG film can be attributed that S‒H shows a stronger electron donor ability and lower carrier scattering than does thiophene-like S‒C. This study is expected to not only promote the potential applications of SG film, but also benefit the fundamental understanding of effect mechanism of sulfur structures on the properties of SG film.