Preparation of Layered-Rhombohedral LiCoO2Epitaxial Thin Films Using Pulsed Laser Deposition

Epitaxial thin films of layered-rhombohedral LiCoO 2 (α-NaFeO 2 structure, R 3 m ) have been successfully grown on Al 2 O 3 (0001) substrates using pulsed laser deposition. A single phase of LiCoO 2 was obtained in the narrow substrate temperature range of 250–300 °C, above which secondary phases, such as Co 2 O 3 , Co 3 O 4 , and LiCo 2 O 4 , appeared. In addition, it was found that annealing of precursor films deposited at room temperature yielded atomically flat LiCoO 2 films with a surface roughness of ∼0.2 nm.