Deposition and dielectric study as function of thickness of perovskite oxynitride SrTaO2N thin films elaborated by reactive sputtering

Abstract

The present study concerns the deposition of perovskite oxynitride SrTaO2N films and their dielectric characterization at low frequencies. Those radio frequency sputtered thin films have been obtained under a reactive plasma (92.3vol.% Ar/7.7vol.% N2) for substrate temperatures ranging from 600 to 900°C. As shown by X-rays diffraction and band-gap measurements, the deposition temperature (TS) determines the film structure and leads to films with band-gap and cell volume approaching the ones of the SrTaO2N bulk material with increased TS. The dielectric study has been performed on polycrystalline, textured and epitaxial SrTaO2N layers deposited on conductive niobium doped SrTiO3 substrates and thickness of films ranging from 30 to 900nm. The related permittivities vary from 66.5 to 90 (@10kHz, room temperature). These low values do not point out an effect of the crystallographic strain of films, due to their thickness, on the permittivity values. The latter remains irrespective of the frequency up to 100kHz and does not vary upon the application of an external DC voltage.