Effect of Co–CoO nanoparticles on the concentration of charge carriers in a hybrid structure based on single-layer CVD graphene

The effect of deposited aggregates of Co–CoO nanoparticles with an average diameter of 160 nm on the charge carrier concentration and carrier transport mechanisms in Co–CoO/graphene/SiO2 hybrid structures has been studied. The structures were obtained by electrochemical deposition of cobalt nanoparticles onto the surface of single-layer CVD graphene in a reverse galvanostatic mode from an electrolyte containing CoSO4∙6H2O (1.25 g/l) and NaCl (0.064 g/l) mixture at a cathodic current density of 2.5 mA/cm2 and an anodic current density 1.25 mA/cm2. It has been shown that deposition of Co–CoO nanoparticles results in an almost twofold decrease in conductivity of structure. We attribute this effect to the exclusion of some of the intrinsic defects of graphene from the carrier transport process in the structure under study.The coexistence of mechanisms of quantum corrections (QC) to the Drude conductivity under conditions of weak localization and usual band (activational) conductivity was discovered. The dominance of the QC to conductivity both before and after the Co–CoO particles deposition, as well as a decrease in the value of the pre-exponential factor σa0, included in the activational mechanism, from 2.8∙10-4 S to 3.1∙10-5 S were observed after particle deposition.