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 [ 1 ¯ 10] MgO. Twin structures formed with in-plane relationships of [010] LiCoO2 // [0 1 ¯ 0] LiCoO2 and [42 1 ¯ ] LiCoO2 // [010] LiCoO2 in the (104) LiCoO2 film and with in-plane relationships of [100] LiCoO2 // [ 1 ¯ 00] 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.