We have studied the formation of the Ag/Ge(111) interface with synchroton radiation photoelectron spectroscopy. We compare the valence band states and the core-level spectra for room temperature adsorption and for different superstructures. Special attention is paid to the square-root 3 x square-root 3 structure since its STM images are identical to those of Ag/Si(111), while a structural analysis by surface X-ray diffraction leads, instead, to a geometry similar to that of Au/Si(111). Our photoemission results support the (rotated) trimer model proposed by the X-ray data.
Lelay, G., Johnson, R. L., Seemann, R., Grey, F., Feidenhans'l, R., & Nielsen, M. (1993). Electronic and crystallographic structures of 2D silver adlayers on Ge(111). Surface Science, 287A, 539-544. https://doi.org/10.1016/0039-6028(93)90838-B