Texture and microstructure development of RF sputter-deposited polycrystalline lithium transition metal oxide thin films

Deposition of polycrystalline lithium transition metal oxide thin films has been performed using radio frequency magnetron sputter deposition on indium tin oxide substrates. Different substrate temperatures, up to 500degreesC, were applied during deposition. The films deposited at elevated temperature exhibited a strong texture (or preferred orientation). It was found that varying the substrate temperature resulted in changing film texture. As the substrate temperature increased, the film structure changed from noncrystalline to polycrystalline with enhanced texture. The film texture and crystallography were examined using X-ray diffraction and transmission electron microscopy. The cross section and surface morphology were observed using scanning electron microscopy. The compositions of the targets and films were characterized by inductively coupled plasma spectroscopy. The deposition technique was used to prepare textured LiCoO2, LiNiO2, LiNi0.8Co0.2O2, and LiMn2O4 thin films. The change of texturing can be interpreted by volume strain energy and surface energy minimization. Film texture of lithium transition metal oxide thin films can be controlled by the substrate temperature. (C) 2003 The Electrochemical Society.