Graphene Grown on Ion-Implanted 4H-SiC and an Effect of Pre-Plasma Treatment

Abstract

4H-SiC substrates were annealed at 1500 °C for 30 min in 0.01 MPa Ar gas flow to make a graphene film. To clarify the effect of Al ion implantation and pre-plasma treatment, the graphene was fabricated on four different kinds of SiC substrates: without plasma treatment, with plasma treatment, Al ion-implanted without plasma treatment and Al ion-implanted with plasma treatment. The graphene films were analyzed by AFM and Raman spectroscopy. The Al ion implanted sample, which was then processed by CF₄ plasma, showed small surface roughness of 3.49 nm (RMS), while the sample without CF₄ plasma treatment showed large surface roughness of 8.41nm. Similar results were also observed for SiC samples without Al ion implantation. In Raman spectra, strong D-band, G-band and 2D-band signals were detected on both ion-implanted samples after annealing at 1500 °C, but weak D-band were observed on both samples without Al ion implantation. Raman mapping (2D-FWHM) showed that the graphene on ion-implanted SiC treated with CF₄ plasma was more homogeneous than the one without CF₄ plasma treatment. Hall measurements for SiC without Al ion implantation showed that graphene on SiC treated with CF₄ plasma has higher mobility (389 cm²/Vs) than that without plasma treatment (136 cm²/Vs). Additionally, p-type graphene can be fabricated on Al ion-implanted SiC by CF₄ plasma treatment.