Characterization of bicrystalline epitaxial LaNiO3 films fabricated on MgO (100) substrates by pulsed laser deposition

A series of metallic LaNiO3 (LNO) thin films were deposited on MgO (1 0 0) substrates by pulsed laser deposition (PLD) under the oxygen pressure of 20 Pa at different substrate temperatures from 450 to 750 degrees C. X-ray diffraction (XRD) was used to characterize the crystal structure of LNO films. theta-2 theta scans of XRD indicate that LNO film deposited at a substrate temperature of 700 degrees C has a high orientation of (1 1 0). At other substrate temperatures, the LNO films have mixed phases of (1 1 0) and (1 0 0). Furthermore, pole figure measurements show that LNO thin films, with the bicrystalline structure, were epitaxially deposited on MgO (1 1 0) substrates in the mode of LNO (1 1 0)//MgO (1 0 0) at 700 degrees C. Reflection high-energy electric diffraction (RHEED) and atomic force microscopy (AFM) were also performed to investigate the microstructure of LNO films with the high (1 1 0) orientation. RHEED patterns clearly confirm this epitaxial relationship. An atomically smooth surface of LNO films at 700 T was obtained. In addition, bicrystalline epitaxial LNO films, fabricated at 700 T, present a excellent conductivity with a lower electrical resistivity of 300 mu Omega cm. Thus, the obtained results indicate that bicystalline epitaxial LNO films could serve as a promising candidate of electrode materials for the fabrication of ferroelectric or dielectric films. (c) 2005 Elsevier B.V. All rights reserved.