La-doped HfO 2 gate dielectric thin films have been deposited on Si substrates using La(acac) 3 and Hf(acac) 4 (acac=2,4-pentanedionate) mixing sources by low-pressure metal-organic chemical vapor deposition (MOCVD). The structure, thermal stability, and electrical properties of La-doped HfO 2 films have been investigated. Inductive coupled plasma analyses confirm that the La content ranging from 1 to 5mol% is involved in the films. The films show smaller roughness of ∼0.5nm and improved thermal stability up to 750°C. The La-doped HfO 2 films on Pt-coated Si and fused quartz substrates have an intrinsic dielectric constant of ∼28 at 1MHz and a band gap of 5.6eV, respectively. X-ray photoelectron spectroscopy analyses reveal that the interfacial layer is Hf-based silicate. The reliable value of equivalent oxide thickness (EOT) around 1.2nm has been obtained, but with a large leakage current density of 3A/cm 2 at V g =1V+V fb . MOCVD-derived La-doped HfO 2 is demonstrated to be a potential high-k gate dielectric film for next generation metal oxide semiconductor field effect transistor applications.