TiO2-SiO2 mixed oxide deposited by low pressure PECVD: Insights on optical and nanoscale electrical properties

TixSi1-xO2 thin films appear as promising materials to replace SiO2 for DRAM devices. For the effective down scaling, these mixed oxides should combine best properties from (low leakage current) and TiO2 (high dielectric constant). In this study, were deposited by low pressure PECVD. Varying Titanium Tetra-Isopropoxide (TTIP) Hexamethyldisiloxane (HMDSO) precursors flow rate allows us obtain nanostructured with tunable properties. Their surface chemical composition was assessed X-ray Photoelectron Spectroscopy (XPS). Atomic Force Microscopy (AFM) revealed that roughness increases Ti content. Spectroscopic Ellipsometry (SE) showed a small amount of is enough induce decrease energy gap an increase refractive index, while preserving roughness. Since oxide exhibit nanodomains three different environments randomly distributed Si-O-Ti bonds, SiO2-like TiO2-like electrical are investigated at nanoscale in terms permittivity, charge injection, trapping transport via modes derived AFM Electrostatic (EFM), Kelvin Probe (KPFM) Conductive (C-AFM). Despite evolving nanoscale, work highlights behavior can be considered homogeneous (at resolution scale). A induces trapped electrons due strong holes. Moreover, after decay These features interpreted on basis diagrams deduced Valence Band measurement highlighting n-type semiconducting character Ti-rich films. As conclusion, x = 0.33 compromise permittivity improvement, injection behavior.