Synthesis of sulfur-doped p-type graphene by annealing with hydrogen sulfide

Doping is an important method to modulate the electronic properties of graphene. Among various types of doped graphene, sulfur-doped graphene is expected to have a wider band gap due to the electron-withdrawing character of sulfur. However, it is difficult to dope graphene with S because S atom is much larger than C atom. In this paper, S-doped graphene is synthesized by a simple method with hydrogen sulfide annealing. It is confirmed by high-resolution transmission electron microscopy diffraction and Raman spectra that S-doping in graphene is surface adsorption doping forming carbon–sulfur compound crystal domains. We are also noted that the doping intensity is affected by annealing time indicating the doping process is controllable. Electrical measurements show that sulfur plays an acceptor role in S-doped graphene leading to a p-type behavior, and after sulfur-doping, graphene exhibits higher resistance and larger on/off ratio.