Gas Sensing Approaches Based on WO3 Nanowire- Back Gated Devices

This paper present a new design and configuration of metal oxide gas sensor based on back-gated device that can operate at low temperature. Gold electrodes patterned onto an oxidized, heavily doped, p-type silicon substrate were designed and fabricated at a wafer level. The Au— electrodes were used as source—drain metal contacts and a third gate electrode was connected from the backside of the substrate. Tungsten oxide nanowires decorated with Pt-nanoparticles were directly grown employing aerosol assisted-CVD (AA-CVD) on top of the electrode area. Gas sensing properties of the back-gated device in the presence of air and hydrogen gas reveals characteristic response modulated by the applied gate potential at room temperature. It was found that the IDSVGS plot illustrates characteristic field effect transistor with an inherent adsorptive surface electron transfer of the nanowires accompanied with the applied gate potential induced charge transfer. These counter-acting mechanisms might persuade for the application of back-gated device as a promising n-channel metal oxide gas sensor operating at low temperature or even room temperature.