Epitaxial growth of fcc-Ag(0 0 1) nanodots on MgO(0 0 1) substrates via Ti seed layer-assisted agglomeration

We have analysed the influence of Ti seed layer (2.0 nm thick) on the agglomeration of Ag films (4.0 nm thick) grown onto MgO(0 0 1) single crystal substrates by RF magnetron sputtering. The samples were deposited at room temperature and post-annealed at 200-450 °C for 4 h while still maintaining the chamber vacuum condition. The surface profile of the sample, as analysed using atomic force microscopy, confirms that the insertion of a Ti seed layer between the MgO substrate and Ag layer promotes the agglomeration process, forming the nanodot. Furthermore, the atomic concentration depth profile of the Ag/Ti/MgO film, as estimated by using angle-resolved x-ray photoelectron spectroscopy, suggests that the nanodot surface mainly consists of Ag. Moreover, x-ray diffraction studies prove that the initial deposition of the Ti seed layer onto MgO(0 0 1) prior to the Ag deposition yields high-quality face-centred cubic (fcc)-Ag(0 0 1) oriented epitaxial nanodots. Based on these results, it can be concluded that the Ti thin film acts as a seed layer, assisting the epitaxial growth of the Ag nanodot onto the MgO substrate.