Surface defects state analysis of laser induced graphene from 4H-SiC

Abstract

We demonstrate the surface defect type, density and related electrical modification of graphene sheet generated by 193-nm ArF excimer laser irradiation on n-type 4H-SiC. The charge density difference and partial density of states (PDOS) carried out by density functional theory (DFT) calculations predict the graphene with lattice imperfection can induce virtual bound states at the vacancy sites and Fermi level shift compared to perfect graphene. The surface defects density of laser generated graphene is characterized by nanoscale electrical measurements using the conductive atomic force microscope (c-AFM). The corresponding current–voltage (I–V) curves show that the electronic charge transfers, thereby electrical conductivities of laser generated graphene, are influenced by the lattice defects. The defect densities are tunable by change laser fluence and pulse number. This research provides an understanding of the interfacial transport properties between laser generated graphene and 4H-SiC through a detailed analysis of surface defects.