Fabrication and electrical characterization of graphene/zinc oxi̇de nanorod hybrid structures

Hybrid structures formed by combining nanostructured materials by changing their geometric dimensions can exhibit extraordinary properties. With the development of technology, higher quality devices are needed and in the future, the most critical needs will be met mostly by low-sized hybrid structures. This study used a low-cost, facile, hydrothermal method to fabricate a zinc oxide (ZnO) nanorod/graphene hybrid structure to produce a highly sensitive CO gas sensor. ZnO nanorods of different diameters were grown vertically on a graphene field effect transistor (GFET) channel to investigate the effect of nanorod diameter on sensor sensing. Developing high-performance, reliable gas sensors that operate at or near room temperature is an important goal of sensor research today. In this study, the ZnO nanorod/graphene hybrid structure meets this demand. The ability of the sensors to operate efficiently at room temperature eliminates the need for extra heating energy, enabling the fabrication of portable, smaller battery-powered sensors. CO gas responses of the fabricated hybrid sensors were reported at room, 50°C and 100°C operating temperatures. The resulting hybrid sensor was found to be effective even at room temperature without requiring an additional operating temperature, giving a sensor response of 42% at 3 ppm CO gas. The hybrid sensor has a short rise time of 4 seconds when 3 ppm CO gas is fed into the measurement chamber. When the gas is removed from the environment at room operating temperature, the recovery time is 5 s. It was observed that gas responses improved with increasing sensor temperature. The thesis also details the working mechanism of the hybrid sensor.