An Indium–Gallium–Zinc–Oxide Layer Decorated With Gold Nanoparticles for Ultrahigh Sensitive Formaldehyde Gas Detection

An interesting formaldehyde (HCHO) gas sensor is fabricated using a sputtered indium&#x2013;gallium&#x2013;zinc&#x2013;oxide (IGZO) layer decorated with gold (Au) nanoparticles (NPs). Based on the use of Au NPs, the efficiently increased surface area to volume (<inline-formula> <tex-math notation="LaTeX">$\textit{S}_{\textit{A}}$</tex-math> </inline-formula>/V) ratio and catalytic reactivity cause the effective enhancement of HCHO gas sensing performance. Experimentally, under 20 ppm HCHO gas, an ultrahigh sensing response of 6855 with a response (recovery) time of 30 s (13 s) is obtained for the fabricated Au NP/IGZO sensor at 225 <inline-formula> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula>C. A lower detectable content of 200 ppb HCHO/air gas at 225 <inline-formula> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula>C is achieved. Furthermore, an improved GM(1, 1) model is used to enhance the prediction ability and meliorate data transmission efficiency within the acceptable reduction error range. This algorithm uses preprocessing to find the starting point of a sensing response and evaluate the influence of noise. This algorithm can efficiently improve the transmission efficiency without increasing the computational complexity. The studied device also displays the advantages of a simple structure, cost-effective production, and suitable application in the internet of things (IoT).