Effect of post-annealing on structural and electrochemical properties of lithium phosphorus oxynitride thin film

In this study, the structural and electrochemical properties of post-annealed lithium phosphorus oxynitride (LiPON) thin films were confirmed. LiPON thin films were deposited using a radio-frequency sputtering method, and post-annealing was performed in the temperature range of 100-400 degrees C. Compared with the initial as-depo state, the impedance decreased at temperatures of 100 and 200 degrees C, and it again increased at 300 and 400 degrees C. As a result, the lowest impedance was seen at 200 degrees C, and it increased significantly at 400 degrees C. To verify the cause of the electrochemical changes, the structural properties of the post-annealed LiPON thin films were confirmed using analytical methods, including X-ray diffraction (XRD), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). XRD and SEM analysis showed that the LiPON thin film prepared in this study had a typical amorphous structure and no change in crystal structure and morphology occurred at 400 degrees C. XPS analysis showed that the Li1s/P2p ratio had the greatest effect on the impedance change, according to the postannealing temperature of LiPON thin films. The ionic conductivity evaluation of the five samples showed that 200 degrees C post-annealing was effective in increasing the ionic conductivity of LiPON thin films, and the effect was reproducible.