Correlation between interfacial structure and c-axis-orientation of LiNbO3 films grown on Si and SiO2 by electron cyclotron resonance plasma sputtering

摘要

Thin films of crystalline lithium niobate (LN) grown on Si(100) and SiO2 substrates by electron cyclotron resonance plasma sputtering exhibit distinct interfacial structures that strongly affect the orientation of respective films. Growth at 460-600 degreesC on the Si(100) surface produced columnar domains of LiNbO3 with well-oriented c-axes, i.e., normal to the surface. When the SiO2 substrate was similarly exposed to plasma at temperatures above 500 degreesC, however, increased diffusion of Li and Nb atoms into the SiO2 film was seen and this led to an LN-SiO2 alloy interface in which crystal-axis orientations were randomized. This problem was solved by solid-phase crystallization of the deposited film of amorphous LN; the degree of c-axis orientation was then immune to the choice of substrate material. (C) 2004 Elsevier B.V. All rights reserved.