Low-Temperature Direct PECVD Synthesis of Graphene on Si(100) with Increased Methane Flow: Structure and Photoelectric Properties

Graphene was directly synthesized on monocrystalline Si(100) at 500 °C by microwave plasma-enhanced chemical vapor deposition using an increased CH4/H2 gas flow ratio. Raman analysis revealed spectral features and intensity ratios consistent with the growth of hydrogenated graphene and revealed changes in defect structure, graphene layer number, and self-doping. Atomic force microscopy measurements showed that the surface morphology and local conductivity strongly depended on the growth conditions. The electrical and photoelectrical characteristics of graphene/Si junctions were correlated with the Raman parameters and surface morphology. For the hydrogenated graphene samples synthesized at 500 °C, the photocurrent, short-circuit current, and open-circuit voltage were found to be competitive with those of pristine graphene reference samples grown at 700 °C. The results demonstrate the potential of low-temperature direct PECVD synthesis for graphene/Si optoelectronic devices.