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

Abstract 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 °C. The sensor was annealed under an O2 atmosphere at 500 °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 (Rgas/Rair), ~8000, where Rair is the standby resistance in air and Rgas is the resistance upon exposure to an oxidizing gas) was obtained at 200 °C. The constructed sensor showed excellent NO2 detection performance, selectivity, and repeatability.