Applied Surface Science, Vol.456, 845-853, 2018
Structural and electronic properties of V/Ag(001) films: Effects of substrate temperature and film thickness
The growth mode, structural and electronic properties of vanadium films on Ag(0 0 1) were investigated using low energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and angle-resolved photo-emission spectroscopy (ARPES) techniques. Previously, it was believed that the layer-by-layer growth of vanadium films is possible (for the first 3-4 layers) at the substrate temperature range of 373-428 K, while our results suggest, vanadium prefers to grow in a three-dimensional (3D) island form and Ag segregates on top of vanadium islands. Detailed band dispersion mapping along the high symmetry directions of V(0 01) surface Brillouin zone (SBZ) clearly shows the presence of quantum-well states (QWS) along with the desired bands of V(0 01) surface, due to the formation of Ag/V/Ag(0 0 1)-like structure. At different growth temperatures, a substantial change in the valence band electronic structures are also observed due to the appearance of sp and d derived Ag QWS, spreading all over the valence band, originating from the different island height of the segregated Ag layers. QWS are absent for the low temperature (similar to 108 K) grown films, indicating the absence of Ag-segregation. Furthermore, we compare our band dispersion data with the available theoretical calculations and good agreement between them is observed. Moreover, our results can be a valuable resource for some future research of noble metal-transition metal interfaces in particular in understanding a complexity of the valence band spectra. These results will also help to explain why contradictory results are reported in the literature on monolayer magnetism of V/Ag(0 0 1) system.