Dresden 2009 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 41: GaN: preparation and characterization II
HL 41.8: Vortrag
Donnerstag, 26. März 2009, 11:30–11:45, BEY 154
Optical and magnetic properties of Gd doped GaN — •Ole Hitzemann1, Martin Kaiser1, Enno Malguth1,2, Markus R. Wagner1, Jan H. Schulze1, Wolfgang Gehlhoff1, Axel Hoffmann1, Shalini Gupta2, Ian T. Ferguson2, Martin Röver3, Dong-Du Mai3, and Angela Rizzi3 — 1Institut für Festkörperphysik, Technische Universität Berlin, Germany — 2School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, USA — 3IV. Physikalisches Institut and Virtual Institute of Spin Electronics (VISel), Georg-August Universität Göttingen, Germany
Gd doped GaN is of high interest for spintronics because it shows a ferromagnetic behavior with a high magnetic moment per Gd atom as well as good conductivity at RT. To investigate the coupling mechanism behind the strong magnetization we examined MOCVD and MBE grown samples of epitaxial layers of this diluted magnetic semiconductor containing Gd at concentrations ranging from 1018 cm−3 to 1021 cm−3. p-type and n-type co-doping allowed the investigation of the effect of the position of the Fermi level. We present high resolution photo luminescence (PL) spectra of a doublet peak at 1.7876 eV with a FWHM of 40 µeV in all Gd doped samples which we associate with an internal Gd3+ transition. The relatively long time constant of 3.5 ms found in time resolved PL experiments confirms the attribution to an intra f-shell transition. Excitation spectra of this luminescence reveal efficient excitation bands between 2.0 and 2.6 eV. The results are discussed in terms of a bound state that might play a significant role in the ferromagnetic behavior reported for GaGdN.