Improved Thermal Stability and Oxygen‐Barrier Performance of SiO2 Thin Films by Modifying Amorphous Network Structure

Abstract

Due to low‐refractive‐index and grain‐boundary‐free features, amorphous SiO2 thin films possess inherent advantages in serving as antireflective and protective layers against atmosphere. However, under high‐temperature and/or oxidation harsh environment, the thermodynamic instability of SiO bonds and “depolymerization” process among tetrahedral units [SiO4] would result in their insufficient thermal stability and oxygen‐barrier failure. By taking amorphous network former, small element electronegativity, and high oxide dissociation energy into considerations, low‐level Zr dopant is introduced to induce short‐ and medium‐range structural modification in amorphous SiO2 thin films, aiming to shorten SiO bond length and enhance network connectivity, respectively. As expected, the fabricated SiZrO thin films exhibit superior thermal stability and oxygen‐barrier performance without sacrificing their low‐index attribute. The Zr doping significantly elevates the oxygen‐inward‐diffusion activation energy from 0.94 to 1.95 eV in SiO2 network. Further, utilizing as protective layer for W‐SiO2 cermet, the SiZrO can effectively prevent the oxidation of W nanoparticles caused by oxygen inward diffusion. Undoubtedly, the exploration of amorphous SiZrO thin films offers exciting prospects for the application of functional coatings and devices under extreme conditions.