Direct growth of high quality graphene nanowalls on dielectric surfaces by plasma-enhanced chemical vapor deposition for photo detection

A method for direct growth of graphene nanowalls (GNWs) on an insulating substrate by plasma enhanced chemical vapor deposition (PECVD) is reported. The effects of growth temperature, plasma power, carbon source concentration, gas ratio and growth time on the quality of GNWs are systematically studied. The Raman spectrum shows that the obtained GNWs have a relatively high quality with a D to G peak ratio (ID/IG) of 0.42. Based on the optimization of the quality of GNWs, a field-effect transistor (FET) photodetector is prepared for the first time, and its photo-response mechanism is analyzed. The responsivity of the photodetector is 160 mA/W at 792 nm and 55 mA/W at 1550 nm. The results reveal that the GNWs are promising for high performance photodetectors.