Resonant Photoemission Study of 4f Electrons on the Surface of Semiconductors

B.A. Orłowski, B.J. Kowalski, M. Pietrzyk, and R. Buczko Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw, Poland

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Received: 16 05 2008

The contribution of 4f electrons to the electronic structure of the semiconductor clean surface caused by the surface doping of it by rare-earth metal atoms (Eu, Sm) will be presented. The surface doping was performed by the controlled, sequential deposition of the rare-earth metal atoms on the clean surface in UHV conditions (Sm on GaN or CdTe) or by the doping of the layer volume of (EuGd)Te. After each deposition or surface treatment the synchrotron radiation was used to measure in situ the resonant photoemission spectra (the Fano type resonance) to study the contribution of 4f electrons of divalent and trivalent Sm and Eu ions to the valence band electronic structure of created sample. The first stages of the metal atoms deposition lead to the surface doping. Further metal atoms deposition leads to the growth of the metallic islands on the surface and causes the appearance of the sharp metallic Fermi edge in the energy distribution curves. Proper coverage and annealing of the sample surface with metal atoms leads to the diffusion of the metal atoms into the sample and results in an increase in the crystal doping and decrease in the metallic islands contribution to the measured spectra. As a result, the new electronic structure of the valence band can be created and investigated in situ.

DOI: 10.12693/APhysPolA.114.S-103 PACS numbers: 79.60.Bm, 71.20.Mq, 07.85.-m