Plasma Treatments for the Low Temperature Crystallization of LiCoO[sub 2] Thin Films

Abstract

As alternatives for the low temperature crystallization of LiCoO2 thin films prepared by radio frequency (rf) reactive magnetron sputtering, two different plasma treatments, microwave and rf plasma treatment, were introduced for the first time. The films deposited at 350°C showed (003) preferred orientation corresponding to a hexagonal layered structure. From X-ray diffraction patterns, it was found that the microwave plasma treatment was effective for enhancing the crystallinity of the as-deposited films. However, the microwave plasma treatment did not enhance electrochemical properties at all, which was associated with the deterioration of surface conditions by the bombardment of energetic particles from the plasma. In the case of rf plasma treatment, the crystallinity improved effectively without severe surface degradation. At the same time, the films treated with rf plasma exhibited relatively good electrochemical properties in comparison with those of bulk LiCoO2 or high temperature annealed LiCoO2 thin films. © 2001 The Electrochemical Society. All rights reserved.

All‐Solid‐State Thin Film μ‐Batteries for Microelectronics

“…LiCoO 2 that has layered rhombohedral structure with a space group at high temperature ( Figure 19 a‐1 ) and slightly distorted cubic structure with a space group Fd 3 m at lower temperature (Figure 19a‐2 ) is one of the intensively studied thin film electrodes. [ 208 , 209 , 210 , 211 , 212 , 213 , 214 , 215 , 216 , 268 ] The lattice structure of LiCoO 2 consists of CoO 2 and Li layers, which are stacked along its c‐axis giving the lattice parameters a and c to be 2.8138 Å and 14.0516Å, respectively. Due to the stacking along the c‐axis, the Li ions in the layered LiCoO 2 only exhibit 2D migration pathways along a ‐ and b ‐axis.…”