Dielectric properties under high electric field for silicon doped alumina thin film with glass-like structure derived from sol-gel process

• Dielectric Si-doped alumina thin films were prepared by sol-gel method.
• AlOSi bonds and cation vacancies VAl''' are produced by substitutive behavior.
• Excellent dielectric properties of Si-doping alumina thin films were achieved.
• The leakage current reduces two orders of magnitude when Si concentration is 2mol%.
• Breakdown strength increased by 93%, comparing with undoped alumina film.

Dielectric Al2-xSixOy (X = 0.00, 0.02, 0.05, 0.10) thin films were deposited onto Pt/Ti/SiO2/Si substrates using sol-gel spin coating technology. The obtained materials were characterized via differential scanning calorimetry (DSC), scanning electron microscopy (SEM), fourier transform infrared spectrometry (FT-IR) and X-ray photoelectron spectrometry (XPS). The results show that the films are amorphous with Si atoms occupying Al atom sites forming AlOSi bonds and glass-like structure. The dielectric properties of the film were investigated. By means of silicon doping, the leakage current and the dielectric loss of the amorphous alumina films much reduced while the breakdown strength enhanced. Two orders of magnitude reduction in leakage current and significant enhancement in breakdown strength (up to 566 MV/m) can be achieved. The improved dielectric properties are attributed to the forming of AlOSi bonds and cation vacancies by the Si-addition. The structure modification enhanced the stability of alumina structure and promoted the ionic transportation to repair the defects of the alumina films.