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 x 2), (1.6 x 2) and (1.5 x 1.8), in regions with low Ba coverage, and their phase diagram was obtained. All Ba atoms which form the c(2 x 2) structure coincide with Mo atoms, and the (1.6 x 2) and (1.5 x 1.8) structures with the regular triangle lattice have line coincidences with the atomic arrangement of the substrate along the [1 (1) over bar0]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. (C) 2000 Elsevier Science B.V. All rights reserved.