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Enhanced dielectric properties of thin Ta2O5 films grown on 65 nm SiO2/Si

: Kolkovsky, V.; Kurth, E.; Kunath, C.


Physica status solidi. C 13 (2016), Nr.10-12, S.786-789
ISSN: 1610-1634
ISSN: 1610-1642
ISSN: 1862-6351
European Materials Research Society (Spring Meeting) <2016, Lille>
Zeitschriftenaufsatz, Konferenzbeitrag
Fraunhofer IPMS ()

The structural and electrical properties of Ta2O5/65 nm SiO2 structures with different thicknesses of Ta2O5 varying in the range of 0-260 nm are investigated. We find that the stack structures grown by the magnetron sputtering technique and annealed at 1220 K in O and Ar atmosphere show one of the highest dielectric constant of Ta2O5(about 64) among those previously reported in the literature. The structure of the annealed polycrystalline Ta2O5 films is orthorhombic, as obtained from X-ray diffraction measurements and we do not observe any preferential orientation of the annealed films. The Ta2O5 films contain positively charged defects which become mobile at around 400 K and they are tentatively correlated with the oxygen vacancies. The leakage current in the stack structures is a factor of 20 higher compared to that in thin layers with 65 nm SiO2. The conduction mechanism in the stack structures can be described by the Fowler-Nordheim model with a barrier height that decreases slightly (<10%) as a function of the thickness of the films.