Leakage current and dielectric breakdown in lanthanum doped amorphous aluminum oxide films prepared by sol–gel

Dielectric Al2−2xLa2xO3 (x=0.00, 0.005, 0.02, 0.05, and 0.10) thin films were fabricated on Pt/Ti/SiO2/Si substrates by sol–gel spin coating. The surface morphology of Al2−2xLa2xO3 thin film was observed by field emission scanning electron microscopy. The chemical state of the lanthanum in aluminum oxide films was analyzed using X-ray photoelectron spectroscopy (XPS), indicating that lanthanum reacts with absorbed water to form lanthanum hydroxide. J–E measurements were used to investigate the current conduction mechanism and breakdown behavior. The results show that La doping changes the conduction mechanism and makes influences on leakage current. The dominating conduction process of 10% La doped Al2O3 films turns into the space charge limited current (SCLC) mechanism in the field region ranging from 25 to 150 MV/m. The leakage current of the films with 10% La doping decreases by three orders of magnitude from 10−6 to 10−9 at the electric field of 25 MV/m. The breakdown strength increases with the increasing content of lanthanum.