Influence of radio frequency power on structure and ionic conductivity of LiPON thin films

Abstract

Lithium phosphorus oxynitride (LiPON) thin films as solid electrolytes were prepared by radio frequency magnetron sputtering of a Li3PO4 target in ambient nitrogen atmosphere. The influence of radio frequency (rf) power on the structure and the ionic conductivity of LiPON thin films has been investigated. The morphology, composition, structure and ionic conductivity of thin films were characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and a.c. impedance measurement. It was found that ionic conductivity of LiPON thin films increases with N content in thin films. XPS measurements reveal that ionic conductivity also keeps relativity with the structure of thin films. Higher the N t/N d ratio, higher will be the ionic conductivity of LiPON thin films. And both of them can be improved by increasing rf power from 1·5 W/cm2 to 5·5 W/cm2.