Development of ultrasensitive indium oxide layer with high response to NO2 gas in indium gallium zinc oxide stack structure using atomic layer deposition

An indium gallium zinc oxide (IGZO)-based sensor was fabricated using atomic layer deposition (ALD) to detect NO2 gas. A unique IGZO film with a thickness of approximately150 nm was deposited to form a stack structure (ZnO/Ga2O3/In2O3) at 150 degrees C. The sensor was annealed under an O-2 atmosphere at 500 degrees C for 1 h. The annealing of the stack structure resulted in an exceptionally active In2O3 sensing layer on top of a Zn/Ga oxide layer, which significantly enhances the sensing performance. Using In2O3 on the top of the stack shows a higher sensor response compared with using ZnO as the top layer. The highest response (i.e., S (R-gas/R-air), similar to 8000, where R-air is the standby resistance in air and R-gas is the resistance upon exposure to an oxidizing gas) was obtained at 200 degrees C. The constructed sensor showed excellent NO2 detection performance, selectivity, and repeatability. (C) 2021 Published by Elsevier B.V.