Ultra-sensitivity and low detection limit of hydrogen gas sensor using high-resolution tin oxide nano-patterns

Abstract

Currently, the roles of gas sensors in various industrial fields are becoming important. Gas sensors go beyond simply detecting gases and play a huge role in ensuring our safety and avoiding potential hazards. In particular, as the number of industrial fields using Hydrogen gas increases according to the importance of eco-friendly energy and sustainable energy, the importance of detecting low level of Hydrogen gas is increasing for explosion prevention and securing safety. In this study, metal oxide based gas sensor that can detect relatively low level of Hydrogen was fabricated through Secondary Sputtering Lithography (SSL). Pd (Palladium), which acts as a catalyst in detecting Hydrogen, and $SnO_2$, mainly used for n-type resistive gas sensors due to its wide band gap energy, are sequentially deposited. Then, Pd-doped $SnO_2$ nano-pattern with small particle size of Pd which is doped regularly, and high aspect ratio (~15) was obtained. We can achieve significant sensitivity and selectivity with larger surface area for gas adsorption and desorption, and better catalytic and spill-over effect through small particle size (< 2.5 nm) of regularly doped Pd simultaneously. In particular, the sensor fabricated in this study has a significant advantage in that it can detect even lower ppb level (20 ppb) of Hydrogen beyond ppm level, which is the Limit of Detection (LOD) of most metal oxide based gas sensors studied in the past.