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Gd atoms on Si (111) surface – AFM and photoemission study

Bronislaw A. Orlowski 1Bogdan J. Kowalski 1Elżbieta Guziewicz 1Elżbieta Lusakowska 1Victor Osinniy 1Iwona A. Kowalik 1Mieczyslaw A. Pietrzyk 1Elzbieta Nossarzewska-Orlowska 2Andrzej Bukowski 2Robert L. Johnson 3

1. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland
2. Institute of Electronic Materials Technology, Silicon Department (ITME), Wólczynska 133, Warszawa 01-919, Poland
3. University of Hamburg, Institute for Experimental Physics, Luruper Chausse 149, Hamburg D-22761, Germany


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 GdX Si1-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.


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Presentation: Poster at E-MRS Fall Meeting 2007, Symposium I, by Bronislaw A. Orlowski
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-21 16:41
Revised:   2009-06-07 00:44