The Humidity-Induced Sensitivity Amplification Effect in an Ionization Gas Sensor With Silicon Nanostructures

This letter reports a significantly amplified response towards organic and inorganic target gases induced by a small variation of humidity for an ionization sensor, which is based on silicon hybrid micro-nanostructures. By introducing Si nanowire arrays using metal-assisted chemical etching, a boosted dynamic range could be achieved with increasing relative humidity read from I-V characteristics. With dry air as carrier gas, the 5000-ppm ethanol vapor sample of 60% relative humidity showed almost two magnitude higher response and signal-to-noise ratio than those of dry ethanol vapor. This humidity amplification effect brought by micro-needle array -Si nanowires hierarchical structure renders the devices especially suitable for working under highly humid environments with optimal performance.