凯发

Graphene, single-layer graphite, has very special properties and potential use in many fields. Hydrocarbon chemical vapor deposition on transition metals gives a practical method for mass production of graphene. In our work, we use a scanning tunneling microscope (STM), which allows scanning while changing temperature up to 1300 K, as well as provides sub nanometer resolution. The growth process of graphene on Rh (111) during ethylene deposition was measured in situ, and a quantitative analysis of the growth process was performed. This revealed several special features of the growth kinetics, which cannot be observed with other techniques. For example, we discovered that the moiré patterns of graphene are not just interference between to lattices, but really play a role in the growth of graphene. We also learned that one of the rate limiting processes in graphene growth is the formation of new kinks at the edge of the growing graphene overlayer. It can be influenced by the detailed morphology of graphene, e.g. it is easier to create a kink at small-angle corners in the graphene overlayer than on a straight edge. This barrier difference in the formation of graphene results in differences in carbon adatom density for different graphene morphologies, for example between the densities of adatoms in contact with inner or with outer contours of graphene. This carbon adatom density difference further determines the carbon dissolution or segregation.