Sol-gel derived SiOx:TiOy films for integrated optics: HR S/TEM and AES/ XPS insight to structure and chemical composition

Comprehensive studies on SiOx:TiOy composite waveguide layers with a high refractive index (n = 1.8), synthesized through sol-gel and dip-coating techniques are presented. The layers' structural and microchemical properties are determined using methods with different spatial resolutions (nm/mu m/mm) and information depths (surface/bulk): optical transmittance, ellipsometry, transmission electron microscopy, Raman spectroscopy, Auger electron spectroscopy combined with ion profiling, and X-ray photoelectron spectroscopy. In the SiOx: TiOy films, 5 nm). Different Si- and Ti-rich phase formation mechanisms linked to alkoxide oxidation rates are found. The film composition (x = 1.1, y = 2.1) and homogenous in-depth O, Ti, and Si concentration profiles were determined. The Si/(Ti + Si) = 0.5 matching the synthesis procedure, oxygen deficiency (O/(Ti + Si) = 1.66), and oxygen vacancies in the silica phase are observed, with AES/XPS chemical shifts providing insights into bonding configurations. The SiOx:TiOy structural/chemical properties correlate well with exceptional optical film features.