Amorphous LaAlO3, high-kappa oxides were grown in a molecular beam epitaxy reactor on p-Si(001) employing a thin gamma-Al2O3 epitaxial layer as buffer. Interfaces are free of SiO2 and silicates and remain abrupt even after high temperature annealing as demonstrated by x-ray photoelectron spectroscopy. Electrical measurements performed on as-deposited samples reveal dielectric constant values close to the bulk ones, small equivalent oxide thickness, and low interface state densities. Some negative charges are present leading to a flatband voltage shift. Postdeposition annealing can correct this effect. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3065437]