Dielectric films of La2O3, HfO2, and LaxHf1-xOy were synthesized by metal-organic chemical vapor deposition. Structural, chemical, and luminescence properties of the films were studied using X-ray photoelectron spectroscopy, methods of X-ray diffraction and selected area electron diffraction, high-resolution transmission electron microscopy, and a cathodoluminescence technique. It was found that doping of hafnium oxide with lanthanum leads to the formation of a continuous series of solid solutions with a cubic structure. This process is accompanied by the formation of oxygen vacancies in the HfO2 lattice. Cathodoluminescence spectra of the LaxHf1-xOy/Si films exhibited a wide band with the maximum near 2.4-2.5 eV, which corresponds to the blue emission. Quantum-chemical calculations showed that this blue band is due to oxygen vacancies in the HfO2 lattice. (C) 2016 Elsevier B.V. All rights reserved.