POLE FIGURE STUDIES OF LaNiO3 FILM PREPARED ON VICINAL MgO (100) SUBSTRATE BY PULSED LASER DEPOSITION

Abstract

ABSTRACT The metallic oxide LaNiO3 (LNO) thin films with pseudo-cubic perovskite structure were prepared on vicinal MgO (100) substrate by pulsed laser deposition (PLD) under the optimum conditions of substrate temperature and oxygen pressure. Phase formation of LNO films were obtained directly during the deposition process itself, without the need for annealing. To examine the structural quality and crystalline orientation of LNO films, the micro-structural and textural analyses of LNO films were carried out by x-ray diffraction (XRD). The single-phase LNO films were fully crystallized, showing a (ll0) preferred orientation in the ω /2θ scans and exhibiting a good in-plane epitaxy in the φ-scans. Finally a complete LNO (111) pole figure was measured and discussed, revealing that the as-grown film was basically high-quality epitaxial film due to similar lattice constant and comparable coefficients of thermal expansion between the film and the substrate and indicating that LNO films can be used as an electrode in ferroelectric devices. It is noteworthy that we firstly observed the twin structure inside LNO films by XRD both φ-scans and pole figure, suggesting that the twin structure of LNO films have been attributed to the presence of vertical lattice mismatch between the film and the steps on the substrate surface.