Deposition of LiNbO3 thin films on diamond/Si(100) substrates for high frequency surface acoustic wave filter applications

摘要

Filters operating at high frequencies up togigahertz are required in telecommunications in order to increasethe rate of data transmission. The goal of this research is toproduce gigahertz electronical filters with low insertion loss forfront-end radio frequency filters by fabricating LiNbO3 thin filmsurface acoustic wave filter devices on diamond-coated siliconchips. In this paper, the deposition of LiNbO3 thin films ondiamond /Si(100) substrates by a metal-organic decompositionprocess is reported. X-ray diffraction analysis shows that thefilms are highly textured polycrystalline LiNbO3 with a (012)orientation. Planview and cross-section scanning electronmicroscopy indicate that the LiNbO3 thin films have dense,smooth surfaces without cracks and pores, and they adhere verywell to the diamond /Si(100) substrates. The grain size is in therange of ~0.2-0.5μm. Atomic force microscopy reveals anaverage surface roughness of about 25 nm.