Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 31: Surface and Interface Magnetism I (jointly with MA)

O 31.5: Vortrag

Dienstag, 12. März 2013, 11:30–11:45, H33

Wave function imaging of transition metal impurities near the H/Si(111) surface — •Benjamin Geisler and Peter Kratzer — Fakultät für Physik and Center for Nanointegration, Universität Duisburg-Essen, 47048 Duisburg, Germany

Despite the difficulties encountered in fabricating magnetic semiconductors, doping of silicon by 3d transition metals is an interesting topic in the field of spintronics. Imaging of electronic states on the atomic scale is possible with state-of-the-art scanning tunneling microscopy (e.g., Jancu et al., PRL 2008, for Mn:GaAs) and can improve the understanding of impurity-host and impurity-impurity interactions.

Here we present an ab initio viewpoint on Cr, Mn and Fe impurities near the H/Si(111) surface, which has the specialty of providing a similar chemical environment as bulk Si does, while keeping the impurities accessible to surface analysis techniques. According to our calculations, subsurface doping through the H layer is possible. We discuss magnetic and energetic characteristics of isolated impurities and their detection with (magnetic) scanning tunneling microscopy, which is able to discriminate between interstitial and substitutional defects of different depth. Furthermore, delta layers and 2D clusters of interstitial impurities and their magnetic properties are shown. We find that the impurity wave functions are less extended than those of Mn in GaAs, which makes it harder to get ferromagnetic coupling in Si.