C. Ab initio calculations; C. High pressure; D. Electronic structure; D. Elastic properties; D. Optical properties

The semiconductor behavior of graphene oxide (GO) and reduced graphene oxide (RGO) synthesized by the Hummers method on n-type Si(111) were investigated. Graphene oxide is a product of the oxidation of graphite, during which numerous oxygen functional groups bond to the carbon plane during oxidation. RGO was prepared by adding excess hydrazine to the GO showing p-type semiconductor material behavior. In the C–O bond, the O atom tends to pull electrons from the C atom, leaving a hole in the carbon network. This results in p-type semiconductor behavior of GO, with the carrier concentration dependent upon the degree of oxidation. The RGO was obtained by removing most of the oxygen-containing functionalities from the GO using hydrazine. However, oxygen remaining on the carbon plane caused the RGO to exhibit p-type behavior. The I–V characteristics of GO and RGO deposited on n-type Si(111) forming p–n junctions exhibited different turn-on voltages and slope values.