Samarium-doped ceria (SDC) and gadolinium-doped ceria (GDC) thin films were formed by e-beam vapor deposition on SiO₂ substrate, changing the deposition rate and substrate temperature during the deposition. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-Ray spectrometry (EDS) were employed in order to investigate the structure ad morphology of the films. A single Raman peak describing the structure of undoped CeO₂ was observed at a frequency of 466 cm⁻¹. Doping of cerium oxide with rare-earth elements shifted the peak to lower frequencies (for Sm—462 cm⁻¹). This shift occurs due to the increased number of oxygen vacancies in doped cerium oxide and it depends on the size and concentration factor of the dopant. It was found that wavenumbers and their intensity differed for the investigated samples, even though the peaks resembled each other in shape. The indicated bands for doped ceria originated as a result of the Raman regime (F2g) of fluorite dioxide associated with the space group (Fm3m). The observed peak‘s position shifting to a lower frequency range demonstrates the symmetric vibrations of oxygen ions around Ce⁴⁺ ions in octahedra CeO₈. Raman shift to the lower frequencies for the doped samples has two reasons: an increase in oxygen vacancies caused by doping cerium oxide with rare-earth materials and the size factor, i.e., the change in frequency Δω associated with the change in the lattice constant Δa.