Ultra-Fast Response ALTP Thermal Gas Flow Sensor Based on Si₃N₄/AlN Composite Insulating Structure

Due to the intrinsic fast response characteristic of the atomic layer thermopile (ALTP) structure compared to the conventional thin film thermopile, the ALTP thermal gas flow sensor shows encouraging potential in fast gas flow detection. However, the thermal conduction delay between the ALTP film and the heating film still restricts the response speed. In this work, the prepared Si₃N₄/AlN composite films significantly reduced the thickness of the insulating layer while ensuring reliable insulation properties. Therefore, the response time of the ALTP thermal gas flow sensor was significantly reduced to 0.1 ms. Meanwhile, the sensor also demonstrated reliable and regular response signals in the tests of different gases, with different thermal sensitivity S*(N₂) > S*(O₂) > S*(Ar), conforming to the characteristics of thermal gas flow sensors. This work may promote the application of the ALTP sensor in high-speed gas flow detection.