Microstructure comparison between KNbO3 thin films grown by polymeric precursors and PLD methods

KNbO3 (KN) thin films were prepared by both Pulsed Laser Deposition (PLD) and Polymeric Precursor Route (PPR) onto polycrystalline alumina (Al2O3) and single-crystalline (100) SrTiO3 substrates. Structural and microstructural characteristics of the thin films were determined by X-ray diffraction, field emission scanning electronic microscopy and electron channeling patterns in order to establish a correlation between the preparation method and the samples characteristics. It was evidenced that both methods are able to produce well crystallized single phase films presenting an epitaxial growth along 110 direction onto (100) SrTiO3 substrates. PLD led to a highest crystalline quality (Δω∼0.25° for PLD and Δω∼1° for PPR), while PPR provides crystallization at lower temperatures, without the appearance of secondary phases. The most remarkable difference between the methods concerns the film morphology (grain size and shape). In fact, deposition by these two routes gives access to various microstructures which open the way to specific study of physical behavior which currently depends on it.