Textured silicon surface and silicon nanowires on silicon chip for ammonia sensing application

Abstract

A low cost, easily processable, highly stable and reproducible, room temperature ammonia gas sensors have been developed using textured silicon and silicon nanowires (SiNWs) on silicon chip as sensing element. The vertically-aligned rice-straw-like SiNWs have been fabricated on silicon chip using metal-assisted chemical etching (MACE) technique. The prepared SiNWs shows dense (37.5%) and well-oriented arrays having heights and diameters of nanowires ranging 4–5 and 50–200 nm, respectively. Ammonia sensing characteristics of the fabricated devices are recorded upon exposes to environment with ammonia molecules of different concentrations (40–100 ppm) at room temperature. The SiNWs based ammonia sensor show low noise and a high response (184%) for 100 ppm ammonia gas. The SiNW-array on silicon chip effectively increases the surface area and possesses good sensing properties and has the potential for mass production of sensing devices.