Surface Acoustic Wave-Based Infrared Sensor With Aluminum Nitride Films Deposited

Abstract

This paper reports on a surface acoustic wave-based infrared sensor with an aluminum nitride thin film deposited on interdigital transducers. The result of the coupling-of-modes (COM) modeling provides an optimized 0.64 mm x 1.80 mm design for interdigital transducers. The sensor resonates at 251.35 MHz with an insertion loss (IL) of -11.80 dB, and the IL difference between the central peak and the second peak is 5.89 dB, which is sufficient for signal processing. The area ratio of the deposited photoelectric film on the device determines the characteristics of the frequency response of the sensor. The response to the intensity of infrared irradiation exhibits good linearity of 99.85% at a wavelength of 850 nm when the thickness and area ratio of the deposited aluminum nitride thin film is 50 nm and 75%, respectively. When the response cycles are observed against infrared light, the sensor not only reacts at high speeds but also returns to the initial state rapidly. The effects of location, including the distance and angle between the light source and the sensor, are also suitable for practical application.