Effect of high pressure annealing on defect structure of GaMnAs
|Przemysław Romanowski 1, Jadwiga Bak-Misiuk 1, Elzbieta Dynowska 1, Andrzej Misiuk 2, Jaroslaw Domagala 1, Elżbieta Lusakowska 1, Janusz Sadowski 1, Wolfgang Caliebe 3, Adam Barcz 1,2|
1. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland
A rapid development of spintronics is observed recently. This exciting new field of research combines magnetism and electronics or optoelectronics. The best materials are so called diluted magnetic semiconductors, i.e. mixed crystals based on classical semiconductors, with a controlled fraction of nonmagnetic atoms being substituted by the magnetic ones, e.g. in GaMnAs.
The 001 oriented GaMnAs layers were grown by the MBE method. The samples were subjected to processing at temperatures T, up to 650 K for 1h under 105 Pa and up to 920 K under high hydrostatic pressure (HP = 1.1 GPa) in argon atmosphere.
The defect structure of samples was determined by high resolution X-ray diffraction methods using conventional and synchrotron radiation sources (HASYLAB-DESY). Synchrotron radiation in the grazing incident diffraction geometry was applied to examine the near-surface region of samples. Conventional X-ray investigations were carried out using MRD-PHILIPS diffractometer in the double and triple axis configurations. Lattice parameters for GaMnAs, before and after the treatment, were measured. Reciprocal space maps for (004) symmetrical reflections were registered. Roughness in the direction perpendicular to the surface and Mn depth profiles were determined using Atomic Force Microscopy and Secondary Ion Mass Spectroscopy, respectively.
The temperature-pressure treatment makes it possible to modify the GaMnAs structure. The high pressure treatment effects in changed diffusivity of Mn interstitials in GaMnAs. Enhanced pressure applied during annealing of the MBE grown layers results in increased strain. Changed strain, from the compressive to tensile one, can be related to a creation of zincblende Mn(Ga)As nanoclusters. A creation of nanoclusters under HP-T conditions is more effective than that caused by annealing under 105Pa.
Acknowledgements:The work was partially supported by the Ministry of Education and Science of Poland under the grant No. N20205232/1189.
Presentation: Poster at E-MRS Fall Meeting 2007, Symposium H, by Przemysław Romanowski
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-14 15:42 Revised: 2009-06-07 00:44