Metal-free synthesis of few-layer graphene films on insulating SiO2 and SiC substrates by chemical vapor deposition

Recently, metal-catalyzed chemical vapor deposition (CVD) has attracted intensive interest as a process for preparing single crystal graphene. However, graphene prepared with metal-catalyzed CVD must be transferred onto an insulating substrate in order to be developed into useful electronic devices, which inevitably degrades its quality and introduces contamination. In this regard, we successfully developed an approach of growing few-layer graphene directly on SiO2 and SiC without metal catalysts, which uniformly covered the entire substrate surface. Under the optimal growth conditions for each case, a faster growth rate was seen for SiC comapring with SiO2. The surface morphology and crystalline quality of the graphene have been characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy, which reveals different growth mechanisms on SiO2 (SK mode) and SiC (VM mode). Hall bar devices have been fabricated with graphene grown on both SiO2 and SiC substrates, revealed high Hall mobilities: 608 cm(2)V(-1)s(-1 )and 1265 cm(2)V(-1)s(-1), respectively. These results provide important knowledge on the future application of graphene in the field of microelectronic devices.