Influence of oxide film surface morphology and thickness on the properties of gas sensitive nanostructure sensor

Abstract

In this study, the gas sensitive metal-oxide semiconductor (MOS) nanostructure sensors based on Ni thin film have been fabricated. The influences of SiO₂ film surface morphology and thickness on the response (R%) and electrical properties of the sensors have been investigated at 150 °C. The surface morphology of the SiO₂ film has been characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The C-V curves of the MOS nanostructure sensors in pure nitrogen and 2 % hydrogen have been reported as well. For the SiO₂ film thicknesses of 14, 65 and 74 nm the measured flat-band voltages (V_FB) are 0.7, 1.5 and 2 V, respectively. The responses of different sensors in 2% hydrogen for SiO₂ film thicknesses of 14 and 74 nm are 84% and 32%, respectively. The MOS nanostructure sensors exhibited good response to the hydrogen gas, with excellent sensitivity. The MOS nanostructure sensor based on Ni thin film and SiO₂ film thickness of 14 nm shows high response and sensitivity.