Thickness Dependency of Thin-Film Samaria-Doped Ceria for Oxygen Sensing

High-temperature oxygen sensors are widely used for exhaust gas monitoring in automobiles. This particular study explores the use of thin-film single crystalline samaria-doped ceria as the oxygen sensing material. Desired signal-to-noise ratio can be achieved in a material system with high conductance. From previous studies, it is established that 6 atomic percent samarium doping is the optimum concentration for thin-film samaria-doped ceria (SDC) to achieve high ionic conductivity. In this study, the conductance of the 6 atomic percent samaria-doped ceria (SDC) thin film is measured as a function of the sensing film thickness. Hysteresis and dynamic response of this sensing platform are tested for a range of oxygen pressures from 0.001 to 100 torr for temperatures above 673 K. An attempt has been made to understand the physics behind the thickness-dependent conductance of this sensing platform by developing a hypothetical operating model and through COMSOL simulations. This study can be used to identify the parameters required to construct a fast, reliable, and compact high-temperature oxygen sensor.