R. F. magnetron sputtering deposition of hetero-epitaxial SrxBa1-xNb2O6 thin films:: The role of temperature

Excellent electro-optic properties of SrxBa1-xNb2O6 (SBN:x) crystals motivate the attempts to control the deposition of high ordered SBN thin films with the aim of optical waveguiding and processing integration. We have shown that the stoichiometry approach favours the crystallization of a competitive parasitic phase (SrNb2O6), examined the role of temperature in this competition and investigated two different sputtering deposition processes: the deposition of an amorphous film followed by an annealing step (process 1), and the direct deposition of a crystallized film at high substrate temperature (process 2). The results show that, whatever the deposition process, temperature is able to inhibit the growth of the SrNb2O6 parasitic phase, but at the expense of the SBN crystallites orientation beyond a certain temperature. This forces a compromise between the single SBN phase and the (001) orientation requirements. Due to its intolerance to oxygen, the process 2 raises an additional problem of optical transparency.