Dielectric property and self-repairing capability of silicon and titanium co-doped amorphous alumina thin films prepared by sol–gel technology
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In this article, (Al1−0.02−xSi0.02Tix)2Oy (x = 0.2, 0.9 and 2%) thin films were prepared on Pt/Ti/SiO2/Si substrates using sol–gel technique. The dielectric properties of undoped and Si–Ti co-doped Al2O3 thin films were investigated. The leakage current of (Al0.971Si0.02Ti0.009)2Oy thin film is reduced by 2 orders of magnitude compared with Al2O3 film. Meanwhile, the modified sample exhibits the ultrahigh energy density of 14.01 J/cm3 under the breakdown strength of 647 MV/m, which is an enhancement of 11.26 J/cm3 over that of the undoped Al2O3 film. The improvement of dielectric properties is ascribed to the forming of Al–O–Si, Al–O–Ti bonds and the anodic oxidation of Ti3+, which could strengthen the stability of Al2O3 structure and self-repair the defects of the films under applied electric field. Another reason is that cation vacancies generated by Si–Ti co-doping could effectively prevent the formation of oxygen vacancies and decrease the breakdown probability of the films. This work provides a promising route to dielectric thin films materials for electrical energy storage applications.
This work is supported by the National Natural Science Foundation of China (Grant No. 61761136004) and the Ministry of Science and Technology of China through 973-project (Grant No. 2015CB654601).
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Conflict of interest
The authors declare that they have no conflict of interest.
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