Indium-Doped SnO2 Based Surface Acoustic Wave Gas Sensor with Ba0.6Sr0.4TiO3 Film

Abstract

SnO2-based gas sensors have been widely synthesized and used for the detection of various hazardous gases. However, the use of doped SnO2 in sensing applications has recently attracted increased interest due to the formation of a synergistic effect between the dopant and the host. Moreover, in the case of a surface acoustic wave (SAW) sensor, the piezoelectric material used in the fabrication of the sensor plays a crucial role in defining the response of the SAW sensor. As a ferroelectric material, barium strontium titanate (Ba0.6Sr0.4TiO3) has recently been studied due to its intriguing dielectric and electromechanical properties. Its high acoustic velocity and coupling coefficient make it a promising candidate for the development of acoustic devices; however, its use as a piezoelectric material in SAW sensors is still in its infancy. In this paper, we present the design, fabrication and validation of an indium doped SnO2-based SAW gas sensor on Ba0.6Sr0.4TiO3 thin film for room temperature (RT) applications. Pulsed laser deposition was used to deposit thin films of Ba0.6Sr0.4TiO3 and indium-doped SnO2. Different characterization techniques were employed to analyze the morphology and crystallization of the films. The performance of the fabricated sensor was validated by exposing it to different concentrations of ethanol and then analyzing the recorded frequency shift. The sensor exhibited fast response (39 s) and recovery (50 s) times with a sensitivity of 9.9 MHz/Δ. Moreover, the sensor had good linear response and reproducibility. The fabricated indium-doped SnO2-based SAW gas sensor could be suitable for practical room temperature applications.