Aluminum-doped Zinc Oxide Nanocrystals for NO2 Detection at Low Temperature

In this work, we focus on nitrogen dioxide (NO2) detection at temperature up to 100 degrees C in order to be compatible with most of flexible substrates. Such low temperatures require dedicated materials, as Zinc Oxide (ZnO), a widely used material for its sensing properties. Functionalization or doping is a growing research activity to improve sensor sensibility at lower gas concentrations and lower working temperatures. Aluminum-doped Zinc Oxide (Al-ZnO) has been shown as a possible way for NO2 detection. Moreover, nanocrystals improve the gas detection due to their high surface/volume ratio. Therefore in this work, Al-ZnO nanocrystals have been deposited by drop coating from colloidal solution as sensitive layer for air quality monitoring. The platform consists of Ti/Pt interdigitated electrodes on Si/SiO2 substrate. Herein, a brief description of the process steps will be provided. Gas sensing properties have been investigated in dark and under ultraviolet illumination at various heating excitation from room temperature around 25 degrees C up to 100 degrees C. These sensors present repeatable responses toward (NO2) with fast responses for low gas concentrations as low as 0.2 ppm.