Control of the surface roughening in the epitaxial growth of manganite films

• Published in: Thin solid films Vol. 495; no. 1; pp. 154 - 158
• Main Authors: Sánchez, F., Infante, I.C., Abad, Ll, Lüders, U., Balcells, Ll, Martínez, B., Fontcuberta, J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 20-01-2006; Elsevier Science
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Electronics; Exact sciences and technology; Interface structure and roughness; Layer-by-layer growth; Magnetic and optical mass memories; Manganite films; Mounds; Physics; Solid surfaces and solid-solid interfaces; Storage and reproduction of information; Surface roughening; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Layer-by-layer growth; Manganite films; Mounds; Surface roughening; Atomic force microscopy; Inorganic compounds; Nucleation; Magnetic tunnelling; Roughness; XRD; Rare earth compounds; Multilayers; Self organization; Topography; Calcium Manganites; Quaternary compounds; Lanthanum Manganites; Grain size; Epitaxial layers; Transition element compounds; Long-range order; Experimental study; Lattice parameters; Thickness; Morphology; Growth mechanism; Tunnel junction
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2005.08.329

To fabricate magnetic tunnel junctions the morphology of the films is a key issue, and two dimensional (2D) growth and very smooth film surfaces are required. In the epitaxy of manganites like La
0.67Ca
0.33MnO
3 (LCMO) above a relatively low thickness a roughening transition is frequently found: growth starts by a layer-by-layer mode, but roughness increases fast as three-dimensional islands form on the surface. We have analyzed the morphology of LCMO epitaxial films and here we report on the roughening process and methods to suppress it. We show that the roughening is due to the formation of multilayered islands. Initially, there are 2D islands on the surface, but before the full coverage of the layer is reached, new 2D islands nucleate and grow on the surface of the existing islands. As new 2D layered islands grow, multilayered mounds are formed. We demonstrate that mounds do not appear if the growth is by step flow mechanism, although there is a marked step meandering. These findings get insight on the epitaxy of complex oxides and provide rules to control the morphology in manganites.