A technique for depositing high-dielectric-constant metal–oxide thin films is demonstrated that consists of alternating pulses of metal–chloride precursors and Hf(NO₃)₄ in which Hf(NO₃)₄ is used as an oxidizing agent as well as a metal source. The use of Hf(NO₃)₄, rather than a separate oxidizing agent such as H₂O, minimizes the potential for oxidation of the Si interface. Unlike HfCl₄, a widely used precursor, the high reactivity of Hf(NO₃)₄ initiates uniform deposition on H-terminated Si beginning with the first pulse. Effective dielectric constants obtained for HfO₂ films produced by this method were comparable to HfO₂ films deposited using other methods and the leakage current densities were three orders of magnitude less than SiO₂ of the same equivalent thickness. Deposition of HfAlOₓ and HfZrOₓ ternary oxide films was also examined. The deposition rate for films produced using this method is greater than one monolayer per cycle, indicating a mechanism that is different from standard atomic-layer deposition.