Structural and dielectric properties of Ba(X1/3Ta2/3)O3 thin films grown by RF-PLD

Ba(X1/3Ta2/3)O3 (X = Mg, Zn) thin films were grown on commercial Pt-coated Si substrates by radiofrequency plasma beam assisted pulsed laser deposition (RF-PLD) method. Single phase Ba(Mg1/3Ta2/3)O3 and Ba(Zn1/3Ta2/3)O3 ceramic targets having an ordered hexagonal structure (with image space group) were used for deposition. Structural, morphological and surface characterizations of the Ba(X1/3Ta2/3)O3 (BXT) films were performed using X-ray diffraction, scanning electron microscopy and atomic force microscopy. X-ray diffraction studies evidenced a cubic (disordered) perovskite structure, with unit cell typical for Pm3m space group. Scanning electron microscopy investigations showed that BXT films have a columnar microstructure, which is oriented perpendicular to the substrate. The temperature dependence of the dielectric permittivity of the films was recorded at 100 kHz. Unlike targets, the BXT films exhibit positive values of the temperature coefficient of the dielectric permittivity. BaMg1/3Ta2/3O3 and BaZn1/3Ta2/3O3 thin films with dielectric constant of about 22.5 and 25, respectively have been obtained.