Si substrates playing two opposing roles in the process of preparing graphene by PECVD

Exposed in plasma excited by a RF coil in a plasma-enhanced chemical vapor deposition (PECVD) process to grow graphene, the silicon substrate is found to play a crucial role. Considering the results of simulations and experiments, the silicon substrate seems to be surrounded by a sheath electric field and consequently changes the local electric field in the vicinity of the substrate surface, which is likely to contribute to the deposition of graphene. In particular, the naturally formed pyramid structure on the top side of a textured silicon wafer turns out localized enhancing the electric field and make the pyramid peak prior to graphene nucleating and growing. Due to the different distribution of the sheath electric field, the pyramid structure on the bottom surface of the same substrate probably suppresses the nucleation and growth of graphene at the same time.