Physical and electrical properties of hafnium-doped tantalum oxide thin films were studied. The doping process affects the structures, composition, thickness, dielectric constant, charges, and leakage current density of both the bulk film and the interface layer. Compared with the undoped film, the lightly doped film exhibited improved dielectric properties, such as a higher dielectric constant, a smaller fixed charge density, a larger dielectric strength, and a lower leakage current. The postdeposition annealing process condition, such as temperature and time, also influences the high-k film's dielectric properties. In summary, the hafnium-doped tantalum oxide film is a promising high-k gate dielectric material for future metal-oxide-semiconductor devices. (c) 2006 The Electrochemical Society. [DOI: 10.1149/1.2180647] All rights reserved.