Local structure of (Ga,Fe)N and (Ga,Fe)N:Si investigated by x-ray absorption fine structure spectroscopy

Abstract

X-ray absorption fine-structure (XAFS) measurements supported by {\em ab initio} computations within the density functional theory (DFT) are employed to systematically characterize Fe-doped as well as Fe and Si-co-doped films grown by metalorganic vapour phase epitaxy. The analysis of extended-XAFS data shows that depending on the growth conditions, Fe atoms either occupy Ga substitutional sites in GaN or precipitate in the form of $\epsilon$-Fe${}_3$N nanocrystals, which are ferromagnetic and metallic according to the DFT results. Precipitation can be hampered by reducing the Fe content, or by increasing the growth rate or by co-doping with Si. The near-edge region of the XAFS spectra provides information on the Fe charge state and shows its partial reduction from Fe${}^{+3}$ to Fe${}^{+2}$ upon Si co-doping, in agreement with the Fe electronic configurations expected within various implementations of DFT.

Minor changes: corrected references [3], [29] and [52]

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Cited by in corpus (11)

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• Structural and paramagnetic properties of dilute Ga1-xMnxN
• Experimental probing of exchange interactions between localized spins in the dilute magnetic insulator (Ga,Mn)N
• Aggregation and magnetism of Cr, Mn, and Fe cations in GaN
• Embedded magnetic phases in (Ga,Fe)N: the key role of growth temperature
• Ferromagnetism of cobalt-doped anatase TiO${}_2$ studied by bulk- and surface-sensitive soft x-ray magnetic circular dichroism
• The Fe-Mg interplay and the effect of deposition mode in (Ga,Fe)N doped with Mg
• Planar arrays of magnetic nanocrystals embedded in GaN
• Element specific characterization of heterogeneous magnetism in (Ga,Fe)N films
• Planar array of self-assembled Ga${}_x$Fe${}_{4-x}$N nanocrystals in GaN: Magnetic anisotropy determined via ferromagnetic resonance