Effect of annealing on the depth profile of hole concentration in (Ga,Mn)As

Abstract

The effect of annealing at 250 C on the carrier depth profile, Mn distribution, electrical conductivity, and Curie temperature of (Ga,Mn)As layers with thicknesses > 200 nm, grown by molecular-beam epitaxy at low temperatures, is studied by a variety of analytical methods. The vertical gradient in hole concentration, revealed by electrochemical capacitance-voltage profiling, is shown to play a key role in the understanding of conductivity and magnetization data. The gradient, basically already present in as-grown samples, is strongly influenced by post-growth annealing. From secondary ion mass spectroscopy it can be concluded that, at least in thick layers, the change in carrier depth profile and thus in conductivity is not primarily due to out-diffusion of Mn interstitials during annealing. Two alternative possible models are discussed.

arXiv comment8 pages, 8 figures, to appear in Phys. Rev. B

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• Strain, magnetic anisotropy, and anisotropic magnetoresistance in (Ga,Mn)As on high-index substrates: application to (113)A-oriented layers
• Absence of halfmetallicity in defect-free Cr, Mn-delta-doped Digital Magnetic Heterostructures
• p-type codoping effect in (Ga,Mn)As: Mn lattice location versus magnetic properties