Chemiresistive gas sensors based on semiconductor metal oxides, such as tin dioxide, help to identify and monitor toxic gases and pollution, and play a vital role in industrial and environmental applications. However, the interfering effect of ambient humidity is a major challenge in their reliable operation, as water molecules on the oxide surface can affect the sensitivity and other characteristics of the sensor. To address this challenge, several surface modifications are being explored in this project. In one approach, we are utilizing atomic layer deposition (ALD), capitalizing on its high coverage and precise thickness control, to deposit a variety of oxides such as alumina after sensor fabrication. The deposited film can be subsequently roughened, resulting in a surface with a high aspect ratio structure that increases the surface area for gas interaction. In another approach, we are modifying the sensor surface by applying thin hydrophobic layers (e.g., hexamethyldisilazane, HMDS) to achieve ultrahydrophobicity, thereby reducing water molecule adsorption and enhancing moisture resistance. This research investigates the impact of ALD deposition parameters on surface morphology, the influence of hydrophobic materials on the oxide interface, and their effects on sensor sensitivity and selectivity. These findings help advance the development of gas sensors that can be adapted to ambient humidity and are expected to be used in a variety of applications.
Project is currently funded by: Member Fees