Thin films of La2Hf2O7 have been deposited by liquid injection atomic layer deposition and post-deposition annealed at 900 degrees C. The dielectric frequency dispersion was more serious for thinner films which is attributed to the effect of a lossy interfacial layer between the La2Hf2O7 dielectric and silicon substrate. The effect of the interfacial layer was modeled based on a dual-frequency measurement technique. The dielectric relaxation of the La2Hf2O7 thin films was modelled using both the Curie-von Schweidler and Havriliak-Negami relationships. Post deposition annealing in nitrogen at 900 degrees C for 15 min improved dielectric relaxation and reduced the dielectric loss. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3043535]