Structural and dielectric properties of oxynitride perovskite LaTiOxNy thin films
Résumé
Oxynitride LaTiOxNy films have been deposited by sputtering with substrate temperature =[800−900 °C] and nitrogen ratio in the plasma =[0−71%]. Distinct nitrogen amounts in films were measured, in agreement with the observed variation of the bang-gap, from Eg=3.45 eV for the transparent film to Eg=2.20 eV for the coloured nitrogen-rich film. The films are polycrystalline, (00l) oriented or epitaxially grown on Nb-doped SrTiO3 substrates. The dielectric constant ε' decreases with increasing nitrogen amount and polycrystalline character of films. The ε' values are high, ranging from 290 to 1220 (room temperature, 10 kHz).