Preparation, Property, and Mechanism Studies of Amorphous Ferroelectric (Ba, Sr)TiO₃ Thin Films for Novel Metal–ferroelectric–metal Type Hydrogen Gas Sensors

Abstract

Ferroelectric (Ba 0.67 Sr 0.33 )Ti x O 3 (BST) thin films with x ‫ס‬ 0.98, 1.00, 1.02, and 1.04 were prepared by the sol-gel technology, and their thermal, structural, dielectric, and gas sensing properties were systematically characterized. The amorphous (Ba 0.67 Sr 0.33 )Ti x O 3 thin film capacitive devices were made on Si substrate to detect hydrogen gas and to study hydrogen-induced interfacial polarization potential. Experimental results showed that the Schottky I-V behavior appears in these Pd/amorphous BST thin film/metal capacitive devices and that enhanced interfacial dipole potentials as large as 4.5 V at 1000 ppm hydrogen gas in air were newly observed, which is about 7 times larger than the best value reported under similar testing conditions. It was clearly shown that the hydrogen-induced interfacial polarization potential is closely correlated with the microstructure of ferroelectric thin films and the enhancement of this interfacial polarization potential is mainly attributed to the high dielectric constant of amorphous ferroelectric thin films. A simple hydrogen interface-blocking model is also presented to explain this interesting phenomenon.

Hydrogen-Sensitive Amorphous Ferroelectric Thin Film Capacitive Devices

“…Comprehensive descriptions on electric properties of amorphous BST and PZT thin film gas sensors are given by Zhu et al [66], Chen et al [57,58], and Deng et al [22]. Microstructural evolution of BST thin films may impact on their I-V characteristics significantly.…”

Effects of interface on the dielectric properties of Ba0.6Sr0.4TiO3 thin film capacitors

“…Polycrystalline barium strontium titanate (Ba x Sr 1Àx TiO 3 , short for BST) thin films are potential materials for the applications of microwave devices such as dielectric phase shifters and tunable filters due to their excellent dielectric properties such as high dielectric nonlinearity, low leakage current, long lifetime, large dielectric breakdown voltage, good temperature stability and adjusting Curie temperature [1][2][3][4][5][6].…”

RF MAGNETRON SPUTTERING CONDITION DEPENDENCES OF DIELECTRIC NON-LINEARITY OF Ba0.6Sr0.4TiO3 THIN FILMS

“…Barium strontium titanate (Ba x Sr 1−x TiO 3 , short for BST) thin films are potential materials for the applications of microwave devices such as dielectric phase shifters and tunable filters due to their high dielectric nonlinearity, low leakage current, long lifetime, good temperature stability and adjusting Curie temperature [1][2][3][4][5][6][7][8]. In particular, dielectric nonlinearity is one of the most important factors for tunable microwave applications.…”