The vacuum deposition of Gd atoms on Si(111) surface leads to the appearance of some unexpected effects. The Gd atom as a next after Eu with configuration Eu 4f⁷6s² it has configuration Gd 4f⁷5d¹6s² of electrons. Lightly bound Gd 5d¹ electron contributes as a donor and Gd atom appears in most chemical compounds as Gd³⁺ ion. The atom is very reactive and in reaction with Si gives a sparking effects. Deposition of Gd atoms by evaporation in UHV on Si(111) leads to creation of craters on Si(111) surface in interface region. Negative magnetoresistance giant effect was observed in low temperatures below 80 K for Gd_X Si_1-X silicide as an effect of RKKY interaction between isolated Gd ions and free carriers.

The paper presents study of Gd atoms deposited on Si(111) surface by means of Atomic Force Microscopy (AFM) and Fano-type resonant photoemission. The layers of thickness 2, 20, 150 and 3000A were deposited in UHV conditions. The remarkably deep craters were observed on silicon surface under deposited 150A of Gd layer. The application of synchrotron radiation in the region of energy hv corresponding to the Gd 4d-4f transition (130 – 170eV) gave the possibility to measure Fano-type resonant photoemission spectra. The spectra of Si valence band with contribution of Gd 4f and 6s electrons were studied for layer of Gd with 2A thick deposited on Si(111) clean surface. The photoemission study gave the curve of the Fano resonance shape with resonance for hv=151,8eV and antiresonance for hv=146,8eV. The Gd 4f localized electrons gave the contribution to the valence band density of states located 9,8 eV below the valence band edge.