A lot of efforts have been recently concentrated on investigation of ferromagnetic semiconductors due to their potential application for spintronic devices . Ferromagnetic GaMnAs is one of materials most interesting for these purposes. The lattice parameter of Ga1-xMnxAs (aL) increases linearly with the Mn content up to x about 0.1. However, different scientific groups (e.g. ) presented rather non-consistent data concerning the aL value dependence on the Mn content. It has been reported, that these discrepancies are due to the presence of different defects, namely of manganese interstitials and arsenic antisites in GaMnAs .
The aim of present work was to determine the influence of substitutional Mn and both mentioned kinds of defects on the lattice parameter value. The concentration of defects was tuned in this work by post-growth annealing of GaMnAs in different temperatures (2400C, 2600C, 2800C). The total Mn concentration in the samples, determined by Secondary Ions Mass Spectrometry (SIMS), remained unchanged after GaMnAs post-annealing. The concentration of substitutional Mn in the GaAs lattice, before and after post-annealing, was determined from the lattice parameter of low temperature (LT) grown GaAs and GaMnAs, subjected to annealing at the same conditions. Based on our results the influence of the substitutional Mn and antisites defects on the lattice parameter of GaMnAs will be discussed.
This work was supported in part within European Community program G1MA-CT-2002-4017 (Centre of Excellence CEPHEUS).
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