Significantly enhanced energy density of amorphous alumina thin films via silicon and magnesium co-doping

The different Si-Mg co-doping content was explored to improve the dielectric properties of amorphous Al2O3 thin film. According to the analysis of DSC, FT-IR, and XPS spectra, it can be confirmed that a novel structure of glass network is formed in the co-doped Al2O3 thin film. More importantly, compared to Al2O3 thin film, the leakage current of (Al.97Si.02Mg.01)2Oy thin film is reduced by 2 orders of magnitude and the breakdown strength is improved from 276 MV/m to 544 MV/m. The corresponding energy density of the modified sample is up to 9.2 J/cm3, which is an enhancement of 6.2 J/cm3 over that of the undoped Al2O3 thin film. Based on finite element analysis, the simulation results show that the applied electric field is mainly focused on the glass network, which could strengthen the stability of Al2O3 structure and decrease the breakdown probability of the films. From the viewpoint of defect chemistry, another reason for the enhancement of the dielectric properties is that Si-Mg co-doping results in the generation of cation vacancies and thus the formation of oxygen vacancies could be effectively prevented. This work could provide a new design strategy for high-performance dielectric capacitor devices.