Effect of substrate temperature on the orientations of radio frequency sputtered Ba2Si2TiO8 thin films

Abstract

The effect of substrate temperature on orientations of rf sputtered Ba2Si2TiO8 (BST) thin films grown on Si (100) and (111) substrates was investigated using x-ray diffraction, optical microscopy, and scanning electron microscopy. The texture of the films deposited on Si (100) substrates varies from an amorphous structure at 750 °C, to a randomly oriented polycrystalline structure, then to (001), (111), (320), and (410) orientations as the substrate temperature increases to 950 °C. The sequence of textures coincides with the decrease in the planar atomic density of the films and the increase in the BST film/substrate interfacial energy for the corresponding orientations. The films deposited on Si(111) substrates show a similar temperature dependency of textures to that observed on films deposited on Si (100) substrates, but the optimum temperature for a particular orientation shifts to higher temperature than that for deposition on Si (100) substrate. The capillarity theory of nucleation is used to explain the growth mechanism of the BST films deposited on Si substrates.