The thermal stability and the resistance to oxygen diffusion of (HfO2)x (Al2O3)y (NiO)1-x-y gate dielectrics deposited on p-type Si (100) substrate by laser molecular beam epitaxy technique (LMBE) have been investigated. X-ray diffraction (XRD) results indicate that the crystallization temperature sig-nificantly increases with Ni and Al added into the HfO2 film. Atomic force microscopy (AFM) testing shows that the surface of these films after annealing in N2 is continuous and flat at the atomic level with no pinhole observed. No silicate interracial layer is found in the high-resolution cross-section transmission electron microscope (HRTEM) images of the (HfO2)x( Al2O3)y(NiO)1-x-y films after 900℃ annealing in N2. It is indicated that the interposed layer of Ni-Al- O between the oxide film and the Si substrate ena-scale.