Effect of reaction time on the dielectric behaviour of reduced graphene oxide–layered cobalt hydroxide composite for high-k gate dielectrics

Abstract

Reduced graphene oxide (RGO)–cobalt hydroxide [Co(OH)2] composite was synthesized using one-pot hydrothermal method. The frequency-dependent dielectric properties and leakage conduction mechanism were studied for the composite. Samples were made with different reaction times of 2, 4, 6 and 12 h for the same concentration of graphene oxide and cobalt nitrate at constant temperature and pH. A high dielectric constant of 7.19×106 with a capacitance of 2.45×10−6 F was achieved for a reaction time of 2 h, at 100 Hz frequency and 27 °C temperature. One order decrement in the dielectric constant (105) was found with an increase in time starting from 4 to 12 h. The leakage current characteristics revealed Schottky barrier-type conduction mechanism in the composites. Thus, RGO-Co(OH)2 composite with a high dielectric constant, microcapacitance and large leakage current could be regarded as a potential high-k candidate, which has its application as a gate dielectric material in the fabrication of metal oxide semiconductor field effect transistor.