FERROELECTRIC (BA0.67SR0.33)TI1.02O3 THIN-FILM H-2 GAS SENSOR BY SOL-GEL DEPOSITION TECHNOLOGY

Ferroelectric (Ba0.67Sr0.33)Ti1.02O3 thin films have been prepared by the sol-gel technology and characterized using thermogravimetric analy sis (TGA), differential thermal analysis (DTA), X-ray diffraction, ato mic force microscopy (AFM), dielectric characterizations, and gas sens ing measurements. These (Ba0.67Sr0.33)Ti1.02O3 thin film gas sensors a re made on Si substrates to detect hydrogen and related hazardous gase s. In such a metal-ferroelectric-metal-silicon (MFMS) structured H-2 g as sensor, dissociated hydrogen H+ ions are accumulated at the metal-f erroelectric BaTiO3 interface, as a result, a dipolar potential is bui lt up in the device. The high dielectric constant of (Ba0.67Sr0.33)Ti1 .02O3 thin films enhances the induced charge at the interface, thus gr eatly improves the sensitivity of H-2 gas detection. Experimental resu lts clearly show that the H-2 gas sensing properties of these ferroele ctric thin film gas sensors are closely correlated with their microstr ucture and the gas sensitivity to hydrogen at 1000 ppm as high as 10 h as been obtained, indicating great promise to fabricate large-scale, S i based ferroelectric gas sensors. Based on our best knowledge, it is the first time in the literature to report this type of ferroelectric thin film device for the hydrogen gas sensor application.