The present invention relates to vacuum-deposited solid state electrolyte layers with high ionic conductivity in electrochemical devices, and methods and tools for fabricating said electrolyte layers. An electrochemical device may comprise solid state electrolytes with incorporated thin layers and/or particles of transition metal oxides, silicon, silicon oxide, or other suitable materials that will induce an increase in ionic conductivity of the electrolyte stack (for example, materials with which lithium is able to intercalate), or mixtures thereof. An improvement in ionic conductivity of the solid state electrolyte is expected which is proportional to the number of incorporated layers or a function of the distribution uniformity and density of the particles within the electrolyte. Embodiments of the present invention are applicable to solid state electrolytes in a broad range of electrochemical devices including thin film batteries, electrochromic devices and ultracapacitors. The solid state electrolyte layers may be nominally pinhole-free.