Electron cyclotron resonance plasma sputtering growth of textured films of c-axis-oriented LiNbO3 on Si(100) and Si(111) surfaces

Abstract

Textured films of c-axis-oriented lithium niobate (LN) in a single Li:Nb=1:1 phase have been grown on Si(100) and Si(111) substrates by electron cyclotron resonance (ECR) plasma sputtering. The O2 partial pressure is critical in determining the composition of the film, whereas the substrate temperature mainly affects crystallinity. At O2 flow rates between 1 and 1.5 sccm and growth temperature between 510 and 550 °C, the refractive indices of the films are within their minimum range. A crystal image of the LN film revealed columnar textured domains, about 40% of which were c-axis oriented. The plasma-enhanced migration of surface atoms is responsible for the polarized grain growth. The amorphous interlayer formed between the LN film and the Si substrate consisted of either a single layer (2 nm) or double component layers (4 nm). The orientation of the LN crystalline overlayer has some correlation with the structure of the underlying amorphous interlayer.