Impact of annealing on material and electrical characteristics of lithium phosphate thin films on silicon carbide

In this study, we investigated the influence of post-deposition annealing (PDA) process on lithium phosphate (Li3PO4) solid-state thin films on silicon carbide (SiC) substrate in terms of materials and electrical properties. Li3PO4 thin films were deposited through radio frequency (RF) sputtering and post-deposition annealing was performed in a temperature range of 200–400 °C. The Li3PO4 thin films show typical amorphous structures, and no changes are observed even after 400 °C PDA process. The Li 1 s/P 2p ratio varies with changing the annealing temperature and the highest Li is detected under 300 °C annealing, where the ionic conductivity increases to 1.00 × 10−4 S/mm at the same temperature. The rectification ratio of the 300 °C annealed device is obtained as 1.45 × 103, which is 23 times higher value than as-deposited Li3PO4/SiC device without annealing. This result suggests that the delicate control of Li3PO4 deposition could provide a significant enhancement on the electrical devices and the solid electrolyte batteries.