ArF excimer laser deposition of wide-band gap solid electrolytes for thin film batteries

High quality solid electrolyte thin films was grown by pulsed laser deposition (PLD) using a high photon energy ArF excimer laser. Various amorphous thin films were successfully deposited on glass substrates from oxide targets; such as Li₃PO₄, LiBO₂, Li₂SiO₃, Li₂CO₃, Li₂SO₄, Li₂ZrO₃, LiAlO₂, Li₂WO₄ and Ohara glass ceramics. The morphology, optical property and ionic conductivity of these films were examined by optical microscope, UV-VIS spectroscopy and impedance analysis. Dramatic improvement of the film morphology was observed by using a high photon energy laser, while the broken film with many droplets was obtained by using lower ones. Ionic conductivity of the films was examined by impedance spectroscopy and dc polarization method. For example, an ionic conductivity of a Li₃PO₄ film was 4.6 × 10^{- 6} S cm^{- 1} at 25 °C with activation energy of 0.57 eV. Electronic conductivity measurements revealed that most of the films were pure lithium ion conductors, while a Li₂WO₄ film was a mixed conductor.