Controlled synthesis of few layer graphene films for gas sensor applications

摘要

A novel approach for synthesis of few layer graphene films on SiC has been developed which uses halogen based inductively coupled-reactive ion etching (ICP-RIE) and rapid thermal annealing (RTA) in atmospheric pressure argon. These films have been characterized using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Surface characterization by XPS reveals the presence of defects similar to those observed for graphene oxide (GO) but at a much lower levels that those observed for GO. As in the case for GO, the defect density could be further reduced by chemical methods which improved carbon to defect ratio based on XPS analyses. Raman spectroscopy showed the presence of D, G and 2D peaks at 1330 cm~(-1), 1599 cm~(-1) and 2671 cm~(-1), respectively, which is comparable with similar graphene films formed by thermal annealing of SiC. The full widths at half max (FWHM) for these peaks was, however, comparable to those observed for GO. Electrical characterization of these graphene films using collinear four point probe measurements showed the electrical resistivity of these films is consistent with the observed values for few layer exfoliated graphene. Gas sensor structures were fabricated using lithography free methods, and initial gas response studies were performed for H_2.