Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 47: GaN: preparation and characterization I
HL 47.6: Vortrag
Donnerstag, 28. Februar 2008, 15:15–15:30, EW 202
Optical and magnetic properties of different Mn centers in GaMnN — •Enno Malguth, Axel Hoffmann, and Wolfgang Gehlhoff — Institut für Festkörperphysik, Technische Universität Berlin, 10623 Berlin, Germany
The potential realization of a ferromagnetic spin-coupling in dilute magnetic semiconductors requires a wide band gap material doped with magnetic ions and with a high concentration of free carriers. Against this background, optical and magnetic experiments were performed on GaMnN samples co-doped with Mg and Si. We observed Mn in the charge states 2+, 3+ and 4+. In detail, we studied the stability of these charge states as a function of the concentration of Mn and of p- or n- co-doping. Our observations can be explained coherently by a shift of the Fermi level. A number of different Mn4+ centers were observed in photo luminescence spectra. We give a tentative identification of Mn4+ related complexes on the basis of temperature, excitation and magnetic field dependent measurements as well as electron spin resonance. Excitation mechanisms of Mn4+ were investigated by means of photo luminescence excitation spectroscopy indicating that the internal excitation of Mn3+ may be part of an efficient excitation process.