Surface structures and growth modes of Ba deposited on Mo(110) surface

The surface structures and growth modes of barium (Ba) on an Mo(110) surface have been investigated using a molecular beam epitaxy system equipped with a high-energy electron diffraction (RHEED) apparatus. Three kinds of surface structures were observed, c(2×2), (1.6×2) and (1.5×1.8), in regions with low Ba coverage, and their phase diagram was obtained. All Ba atoms which form the c(2×2) structure coincide with Mo atoms, and the (1.6×2) and (1.5×1.8) structures with the regular triangle lattice have line coincidences with the atomic arrangement of the substrate along the [11̄0]Mo and [001]Mo directions, respectively. In the thickness range beyond 1 ML, the growth modes of the Ba–Mo(110) system were different due to the substrate temperature. The growth of the Ba–Mo(110) system is in accordance with the Frank–van der Merwe growth mode at room temperature and the Stranski–Krastanov growth mode at high temperatures.