Observation of high dielectric constant of Bi-Nb-O_x thin-film capacitors fabricated by chemical solution deposition process

Abstract

BiNbOx (BNO) thin films fabricated by a chemical solution deposition (CSD) under annealing conditions of 550°C and 20 min were found to exhibit an unprecedentedly high relative dielectric constant of 170, which is substantially greater than that of sputtered BNO films. Transmission electron microscopy analysis showed that the BNO film fabricated by CSD had two crysalline phases, β-BiNbO₄, cubic pyrochlore, along with amorphous regions. In contrast, the BNO film deposited by sputtering consists of Bi₃NbO₇ crystallites and amorphous regions and no cubic pyrochlore phase was found. The presence of the pyrochlore crystallites explains unprecedentedly high relative dielectric constant observed in CSD-derived BNO films.