A STABLE THIN-FILM LITHIUM ELECTROLYTE - LITHIUM PHOSPHORUS OXYNITRIDE

The electrochemical and optical properties of Lithium phosphorous oxyn itride (Lipon) thin films have been studied with an emphasis on the st ability window vs. lithium metal and the behavior of the Li/Lipon inte rface. Impedance measurements made between -26 and 140 degrees C show that Lipon exhibits a single, Li+-ion conducting phase with an average conductivity of 2.3 (+/-0.7) x 10(-6) S/cm at 25 degrees C and an ave rage activation energy of E(a) = 0.55 +/- 0.02 eV. No detectable react ion or degradation was evident at the Li/Lipon interface, and linear s weep voltammetry measurements on three-electrode cells indicated that Lipon is stable from 0 to about 5.5 V with respect to a Li+/Li referen ce. The complex refractive index of Lipon was measured by spectroscopi c ellipsometry. Optical bandgaps of 3.45 and 3.75 eV were obtained fro m the ellipsometry data and from optical absorption measurements, resp ectively.