Leakage Current of Capacitive BST Thin Films

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J. Korean Ceram. Soc. > Volume 34(8); 1997 > Article

Journal of the Korean Ceramic Society 1997;34(8): 803.

BST 축전박막의 누설전류 평가

인태경, 안건호, 백성기

포항공과대학교 재료금속공학과

Leakage Current of Capacitive BST Thin Films

ABSTRACT

Ba0.5Sr0.5TiO3 thin films were deposited by RF magnetron sputliring method in order to clarify the anneal condition and doping effect on loakage current Nb and Al were selected as electron donor and acceptor dopants respectively, in the BST films because they have been known to have nearly same ionic radii as Ti and thought to substitute Ti sites to influence the charge carrier and the acceptor state adjacent to the gram boundary. BST thin films prepared in-situ at elevated temperature showed selatively high leakage current density and low breakdown voltage. In order to achieve smooth surface and to improve electrical properties, BST thin films were deposited at room temperature and annealed at elevated temperature. Post-annealed BST thin films showed smoother surface morphology and lower leakage current density than in-situ prepared thin films. The leakage current density of Al doped thin films was measured to be around 10-8A/cm2, which is much lower than those of undoped and Nb doped BST films. The result clearly demonstrates that higher Schottky barrier and lower mobile charge carrier concentration achieved by annealing in the oxygen atmosphere and by Al doping are desirable for reducing leakage current density in BST thin films.

Key words: BST thin film, Sputtering, Leakage current, Doping effect