Epitaxial growth of (104)- and (018)-oriented licoO₂ films on MgO single crystals prepared by chemical vapor deposition

The lithium cobaltate (LiCoO₂) films were deposited onto single-crystal magnesium oxide (MgO) substrates by metal organic chemical vapor deposition, and the in-plane orientation relationship, morphology and deposition rates were investigated. Hetero-epitaxial LiCoO₂ films oriented to (104) and (018) were obtained on (100) and (110) MgO substrates. The surface morphology of the (104) LiCoO₂ film showed diagonally arrayed rectangular facets, whereas the (018) LiCoO₂ film exhibited a roof-like structure extended unidirectionally to [110] MgO. Twin structures formed with in-plane relationships of [010] LiCoO₂ // [010] LiCoO₂ and [421] LiCoO₂ // [010] LiCoO₂ in the (104) LiCoO₂ film and with in-plane relationships of [100] LiCoO₂ // [100] LiCoO2 in the (018) LiCoO2 film. The deposition rates of the (104)- and (018)-oriented LiCoO₂ films were 10.8 μm h^-1 and 8.8 μm h^-1, respectively, which were almost 100 times greater than those reported for LiCoO₂ epitaxial films fabricated by pulsed laser deposition.