Font Size:
Lattice location of Mn implanted into GaAs: Identification of interstitial Mn and evidence of its high thermal stability
L. M. C. Pereira*, U. Wahl, J. G. Correia, S. Decoster, J. P. Araújo, and A. Vantomme
poster presentation: Tuesday 2010-08-24 05:00 PM - 07:00 PM in section Modification of semiconductors, metals and ceramics
Last modified: 2010-06-02
Abstract
The lattice location of Mn in GaAs has been intensively studied in recent years due to its crucial role on the magnetic properties of (Ga,Mn)As, one of the most studied dilute magnetic semiconductors. Maximum Curie temperatures (TC) are achieved after post-growth processing, typically low temperature annealing (∼200°C), which is generally attributed to out-diffusion of interstitial Mn (MnI). However, despite major developments in film quality even at very high Mn concentrations (up to 10%), the TC of (Ga,Mn)As remains below room temperature.
We report on the lattice location of Mn in heavily p-doped GaAs by means of electron emission channeling from the decay of implanted 56Mn produced at ISOLDE/CERN. We locate the majority of the Mn atoms in substitutional Ga sites and up to 31% in tetrahedral interstitial sites with As nearest neighbors. Contrary to the general belief that interstitial Mn out-diffuses at ∼200°C [1], we give evidence of its high thermal stability up to 400°C, which we attribute to MnI trapping by the acceptor defects. Showing that MnI is immobile up to temperatures where phase segregation is known to occur and that conventional thermal annealing is therefore inadequate to produce pure substitutional doping, we outline ion-beam processing alternatives for the realization of higher TC in (Ga,Mn)As.
[1] K. W. Edmonds, P. Boguslawski, K. Y. Wang, R. P. Campion, S. N. Novikov, N. R. S. Farley, B. L. Gallagher, C. T. Foxon, M. Sawicki, T. Dietl, M. Buongiorno Nardelli, and J. Bernholc, Phys. Rev. Lett. 92, 037201 (2004).
We report on the lattice location of Mn in heavily p-doped GaAs by means of electron emission channeling from the decay of implanted 56Mn produced at ISOLDE/CERN. We locate the majority of the Mn atoms in substitutional Ga sites and up to 31% in tetrahedral interstitial sites with As nearest neighbors. Contrary to the general belief that interstitial Mn out-diffuses at ∼200°C [1], we give evidence of its high thermal stability up to 400°C, which we attribute to MnI trapping by the acceptor defects. Showing that MnI is immobile up to temperatures where phase segregation is known to occur and that conventional thermal annealing is therefore inadequate to produce pure substitutional doping, we outline ion-beam processing alternatives for the realization of higher TC in (Ga,Mn)As.
[1] K. W. Edmonds, P. Boguslawski, K. Y. Wang, R. P. Campion, S. N. Novikov, N. R. S. Farley, B. L. Gallagher, C. T. Foxon, M. Sawicki, T. Dietl, M. Buongiorno Nardelli, and J. Bernholc, Phys. Rev. Lett. 92, 037201 (2004).
Author(s) affiliation:
L. M. C. Pereira*, Instituut voor Kern- en Stralingsfysica and INPAC, K.U.Leuven, 3001 Leuven, Belgium
U. Wahl, Instituto Tecnológico e Nuclear, UFA, 2686-953 Sacavém, Portugal
J. G. Correia, Instituto Tecnológico e Nuclear, UFA, 2686-953 Sacavém, Portugal
S. Decoster, Instituut voor Kern- en Stralingsfysica and INPAC, K.U.Leuven, 3001 Leuven, Belgium
J. P. Araújo, IFIMUP and IN-Institute of Nanoscience and Nanotechnology, DFA-FCUP, 4169-007 Porto, Portugal
A. Vantomme, Instituut voor Kern- en Stralingsfysica and INPAC, K.U.Leuven, 3001 Leuven, Belgium
*presenting author
Conference registration is required in order to view papers.
U. Wahl, Instituto Tecnológico e Nuclear, UFA, 2686-953 Sacavém, Portugal
J. G. Correia, Instituto Tecnológico e Nuclear, UFA, 2686-953 Sacavém, Portugal
S. Decoster, Instituut voor Kern- en Stralingsfysica and INPAC, K.U.Leuven, 3001 Leuven, Belgium
J. P. Araújo, IFIMUP and IN-Institute of Nanoscience and Nanotechnology, DFA-FCUP, 4169-007 Porto, Portugal
A. Vantomme, Instituut voor Kern- en Stralingsfysica and INPAC, K.U.Leuven, 3001 Leuven, Belgium
*presenting author