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

Abstract

Epitaxial thin films of layered-rhombohedral LiCoO2 (α-NaFeO2 structure, R3m) have been successfully grown on Al2O3(0001) substrates using pulsed laser deposition. A single phase of LiCoO2 was obtained in the narrow substrate temperature range of 250–300 °C, above which secondary phases, such as Co2O3, Co3O4, and LiCo2O4, appeared. In addition, it was found that annealing of precursor films deposited at room temperature yielded atomically flat LiCoO2 films with a surface roughness of ∼0.2 nm.