Recently, the DICP Research Group No. 502 has collaborated with the Zhongfan Liu – Hailin Peng research team of the Chemistry & Molecular Engineering College of Peking University to study the surface topology and surface work function of graphenes prepared by the modulation-doped growth method and having a mosaic structure by means of the DUV-PEEM and AC-LEEM techniques. Their investigation confirmed that by employing the chemical vapor deposition process, controlled growth of intrinsic graphene area and nitrogen doped graphene area could be realized. Their results were published in Nature Communication (Nature Commun. 2012, 3: 1280; doi: 10.1038/ncomms2286).
Constructing of p-n junctions is the key step in applying graphenes to photo-electric components, which necessitates stable doping with high controllability and homogeneity. Large-scale preparation of p-n junction materials from mosaic structured graphenes has been achieved by the Zhongfan Liu – Hailin Peng research team of the Peking University, and has been applied to highly effective photo-electric transformation devices. Due to the fact that nitrogen doping can lower effectively the surface work function of graphene, the doped graphene will have big contrast difference with the intrinsic graphene in PEEM imaging. Accordingly, the PEEM technique can be used as an efficient surface approach for the characterization of these kinds of graphene surfaces. The successful experience of the present work illustrated that the PEEM technique can play an important role in chemical-physical researches of solid surfaces.