Ultrasensitive multiple networked Ga2O3-core/ZnO-shell nanorod gas sensors

Ga2O3-based gas sensors show very poor performance at room temperature despite being able to detect a range of gases efficiently at high temperatures of 600–1000 °C, which limits their practical use. This study examined the effect of the encapsulation of Ga2O3 nanorods with ZnO on the NO2 gas sensing properties. Ga2O3-core/ZnO-shell nanorods were fabricated by a two step process comprising the thermal evaporation of GaN powders and atomic layer deposition of ZnO. Multiple networked Ga2O3-core/ZnO-shell nanorod sensors showed the response of 32,778% at an NO2 concentration of 100 ppm at 300 °C. This response value is 692 times larger than that of bare-Ga2O3 nanorod sensors at an NO2 concentration of 100 ppm. The substantial improvement in the response of Ga2O3 nanorods to NO2 gas by the encapsulation by ZnO can be accounted for based on the space-charge model.