(Ba,Sr)TiO₃ thin films by RF multitarget co-sputtering and hydrogen gas sensing properties

Ferroelectric (Ba,Sr)TiO₃ thin films have been prepared by RF co-sputtering process, and characterized using dielectric characterizations and gas sensing measurements for the H₂ detection. Experimental results show that the leakage current of these co-sputtered BST thin films is closely related to the deposition parameters and electronic defects in the films. The I-V performances of our Pd/BST/Pt capacitive devices exhibit the typical Schottky behavior, both in air and in hydrogen gas. The turn-on voltage shift at 1024 ppm H₂ gas diluted in air has been observed due to the H2 blocking effect by BST films at the interface with the catalytic Pd metal layer. It is believed that the electronic defects cause the degradation of the RF co-sputtered films to H₂ gas detection, and weaken the induced H₂ potential build-up across the space charge layer at the interface.