Deposition of potassium lithium niobate films by sol-gel method

Abstract

Potassium lithium niobate (KLN) films have been prepared by sol-gel method using metal ethoxides as starting materials. The films were deposited by spin coating and were annealed in air in a conventional oven as well as in a rapid thermal processor (RTP). X-ray diffraction and Raman scattering measurements have shown that polycrystalline KLN films with tetragonal tungsten-bronze-type structure could be obtained on both SiO₂ buffered Si and fused quartz substrates. Surface morphology studies indicated that RTP annealing could avoid film cracking and enable nanostructured low- surface roughness KLN films to be formed. Optical waveguiding experiments showed that the films have refractive indices close to those of their single crystal and could support several modes. The films deposited on fused quartz were highly transparent in the visible-near IR spectral range and the absorption edges of the films, as determined from the absorption data, were found to shift towards the violet spectral side.