Halogen Based Surface Chemistries for Graphene Synthesis

Abstract

Halogen based (CF4 and Cl2) inductively coupled reactive ion etching (ICP-RIE) has been used to selectively etch silicon from 6H-SiC to produce a controlled number of carbon layers. After annealing at temperatures in the range of 550 °C to 1100 °C to reconstruct the near surface layers, x-ray photoelectron spectroscopy has been used to characterize the composition of the films. For the Cl2 based ICP-RIE, two carbon species are observed. One is due to carbon bound as SiC in the substrate and a second which can be attributed to graphene. In the case of CF4 based etching the situation is similar except the second peak is most closely aligned with p-type graphene. This is most likely due to electron transfer from the graphene to the trace levels of fluorine remaining on the surface after annealing.