Electron microscopy studies of thin Mo films grown by MBE on (100) SrTiO3 substrates

A highly mismatched Mo/SrTiO3 system was found to develop two non-equivalent orientation relationships between the metal film and the ceramic substrate. The molybdenum films, with a nominal thickness of 50 nm, were deposited by molecular beam epitaxy at T-substrate = 600 degreesC. The film and the substrate were investigated by X-ray diffraction, conventional and high-resolution transmission electron microscopy. The following orientation relationships (OR) were determined: OR I {1 1 0} Mo\\{1 0 0}STO; <1 0 0>Mo\\<1 0 0>STO, <1 1 0>Mo\\<1 0 0>STO, OR II {1 1 0}Mo\\{1 0 0}STO; <1 1 1>Mo\\<1 1 0>STO. The interfaces between the different Mo domains and the substrate were examined by high-resolution transmission electron microscopy. All interfaces were found to be abrupt; no significant reaction layer was directly observed. The grain boundaries between the domain variants are special tilt grain boundaries, as determined by high-resolution transmission electron microscopy. Some of the grain boundaries possess a low-energy configuration. The formation of the preferred orientation relationships, the interface features and the possible growth behaviour will be discussed. (C) 2003 Elsevier B.V. All rights reserved.