Formation of Al{sub 2}O{sub 3}-Ta{sub 2}O{sub 5} double-oxide thin films by low-pressure MOCVD and evaluation of their corrosion resistances in acid and alkali solutions
- Tohoku Univ., Sendai (Japan)
Al{sub 2}O{sub 3}-Ta{sub 2}O{sub 5} double-oxide thin films with different cationic mole fractions of Ta, X{sub Ta}, were formed by metallorganic chemical vapor deposition using aluminum tetraisopropoxide [Al(O-i-C{sub 3}H{sub 7}){sub 3}] and tantalum pentametoxide [Ta(OCH{sub 3}){sub 5}] as source gases and oxygen as a reaction gas. The corrosion resistances of the films were examined in 6 and 12 M HCl and 1 M NaOH at 298 K by the ellipsometric measurement of thinning rates of the films. The Al{sub 2}O{sub 3}-Ta{sub 2}O{sub 5} films having X{sub Ta} values between 0.0 and 1.0 showed homogeneous amorphous structures. The thinning rate of the films in HCl solutions decreased with increasing X{sub Ta} value and reached the analytical limit of ellipsometry. The films with X{sub Ta} values larger than 0.35 hardly dissolved in 6 M HCl and those with X{sub Ta} values larger than 0.45 in 12 M HCl. The corrosion resistance of the Al{sub 2}O{sub 3}-Ta{sub 2}O{sub 5} films in 1 M NaOH increased significantly with an increase in X{sub Ta}: the dissolution rate of the Al{sub 2}O{sub 3}-Ta{sub 2}O{sub 5} film with X{sub Ta} value of about 0.5 is lower than that of pure Al{sub 2}O{sub 3} film by six orders of magnitude.
- OSTI ID:
- 328208
- Journal Information:
- Journal of the Electrochemical Society, Vol. 146, Issue 2; Other Information: PBD: Feb 1999
- Country of Publication:
- United States
- Language:
- English
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