Autor: Martin S. Brandt, T. Graf, Martin Stutzmann, L. Görgens, M. Gjukic, Oliver Ambacher
Rok vydání: 2003
Předmět:
Zdroj: Journal of Superconductivity. 16:83-86
ISSN: 0896-1107
DOI: 10.1023/a:1023288718903
Popis: MBE-grown GaN : Mn layers with Mn doping concentrations around 1020 cm−3 were investigated by photoconductivity measurements. From electron spin resonance (ESR), Mn is known to be mostly present in the neutral Mn3+ or Mn2+ + h+ state, which leads to a reassignment of the known optical absorption features to charge transfer from Mn3+, either by direct photoionization at about 1.8 eV or by a photothermal ionization process via an excited state (Mn3+)* at 1.42 V higher internal energy than the Mn3+ ground state. It is proposed that the Mn3+/Mn2+ acceptor level is located about 1.8 eV above the valence band edge of GaN so that the nature of the acceptor wavefunction is very different from an effective-mass-like state such as the Mn2+ + h+ complex in GaAs : Mn. According to these experimental results, the realization of carrier-mediated ferromagnetism becomes rather unlikely in not co-doped GaN : Mn.
Databáze: OpenAIRE
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