Dielectric properties and X-ray photoelectron spectroscopic studies of niobium oxide thin films prepared by direct liquid injection chemical vapor deposition method

• High dielectric constant (47) of Nb2O5 thin film with chemical vapor deposition
• The change in morphology as a function of growth temperature and O2 molar ratio
• A stoichiometric Nb2O5 phase and smooth surface show better electrical properties.

Niobium oxide thin films were grown by direct liquid injection chemical vapor deposition using Nb(OC2H5)5 precursor. Influence of reactant's molar ratios [oxygen:Nb(OC2H5)5] and deposition temperatures on films properties such as growth rate, stoichiometry, crystal structure, morphology, dielectric constant and leakage current were studied. Films start crystallizing above 340 °C in O2 atmosphere and become crystalline at 400 °C. The surface roughness of weakly crystalline and crystalline films was significantly affected by deposition temperatures and reactant's molar ratios. It was found that decrease in surface roughness improved leakage current. X-ray photoelectron spectroscopic studies showed that films were in different oxidation states (Nb2 +, Nb4 + and Nb5 +). The dielectric constants of films were improved by increasing oxygen ratios. At ratio (150:1), the film showed high dielectric constant value (47) at 340 °C and leakage current density of 2.0 × 10− 5 A/cm2 (at 3 V).