rf-sputtering of PMNT thin films

We report on the realization of relaxor ferroclectric thin films by rf magnetron sputtering deposition, We investigated fabrication of films in the solid solution of PMN (Pb(Mg1/3Nb2/3)O-3) with PT (PbTiO3), This material is the most studied among the relaxor ferroelectric family for applications in the field of microelectronics and microsystems. We chose the composition with 30% of PT, close to the morphotropic phase boundary between relaxor and normal ferroelectric behavior which exhibits good piezoelectric properties suited to actuators. We have grown the films in a cold deposition process. The substrates used were Si/SiO2 coated by Ti/Pt electrodes, This allowed to synthesize pyrochlore-free PMNT ceramic thin films at temperatures between 450 and 675 degreesC in a post-deposition conventional annealing. We performed dielectric and ferroelectric characterizations of the films with Pt upper electrodes. Dielectric constant was measured as a function of temperature (up to 155 degreesC) and frequency (1 kHz similar to 1 MHz). We obtained relative dielectric constant of the order of 1500. Relaxor behavior and ferroelectric properties are evidenced and are shown to be enhanced by annealing temperature.