Structural and electronic properties of Fe3+ and Fe2+ centers in GaN from optical and EPR experiments

Malguth, E; Hoffmann, A; Gehlhoff, W; Gelhausen, O; Phillips, MR; Xu, X

Structural and electronic properties of Fe3+ and Fe2+ centers in GaN from optical and EPR experiments

Malguth, E Hoffmann, A Gehlhoff, W Gelhausen, O Phillips, MR

Xu, X

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Publication Type:: Journal Article
Citation:: Physical Review B - Condensed Matter and Materials Physics, 2006, 74 (16)
Issue Date:: 2006-10-12

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Field	Value	Language
dc.contributor.author	Malguth, E	en_US
dc.contributor.author	Hoffmann, A	en_US
dc.contributor.author	Gehlhoff, W	en_US
dc.contributor.author	Gelhausen, O	en_US
dc.contributor.author	Phillips, MR https://orcid.org/0000-0003-1522-9281	en_US
dc.contributor.author	Xu, X	en_US
dc.date.issued	2006-10-12	en_US
dc.identifier.citation	Physical Review B - Condensed Matter and Materials Physics, 2006, 74 (16)	en_US
dc.identifier.issn	1098-0121	en_US
dc.identifier.uri	http://hdl.handle.net/10453/419
dc.description.abstract	This work provides a consistent picture of the structural, optical, and electronic properties of Fe-doped GaN. A set of high-quality GaN crystals doped with Fe at concentrations ranging from 5× 1017 cm-3 to 2× 1020 cm-3 is systematically investigated by means of electron paramagnetic resonance and various optical techniques. Fe3+ is shown to be a stable charge state at concentrations from 1× 1018 cm-3. The fine structure of its midgap states is successfully established, including an effective-mass-like state consisting of a hole bound to Fe2+ with a binding energy of 50±10 meV. A major excitation mechanism of the Fe3+ (T14 → A16) luminescence is identified to be the capture of free holes by Fe2+ centers. The holes are generated in a two-step process via the intrinsic defects involved in the yellow luminescence. The Fe3+/2+ charge-transfer level is found 2.863±0.005 eV above the valence band, suggesting that the internal reference rule does not hold for the prediction of band offsets of heterojunctions between GaN and other III-V materials. The Fe2+ (E5 → T25) transition is observed around 390 meV at any studied Fe concentration by means of Fourier transform infrared spectroscopy. Charge-transfer processes and the effective-mass-like state involving both Fe2+ states are observed. At Fe concentrations from 1× 1019 cm-3, additional lines occur in electron paramagnetic resonance and photoluminescence spectra which are attributed to defect complexes involving Fe3+. With increasing Fe concentration, the Fermi level is shown to move from near the conduction band to the Fe3+/2+ charge-transfer level, where it stays pinned for concentrations from 1× 1019 cm-3. Contrary to cubic II-VI and III-V materials, both electronic states are effected by only a weak Jahn-Teller interaction. © 2006 The American Physical Society.	en_US
dc.relation.ispartof	Physical Review B - Condensed Matter and Materials Physics	en_US
dc.relation.isbasedon	10.1103/PhysRevB.74.165202	en_US
dc.subject.classification	Fluids & Plasmas	en_US
dc.title	Structural and electronic properties of Fe3+ and Fe2+ centers in GaN from optical and EPR experiments	en_US
dc.type	Journal Article
utslib.citation.volume	16	en_US
utslib.citation.volume	74	en_US
utslib.for	0204 Condensed Matter Physics	en_US
utslib.for	02 Physical Sciences	en_US
utslib.for	03 Chemical Sciences	en_US
utslib.for	09 Engineering	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Mathematical and Physical Sciences
pubs.organisational-group	/University of Technology Sydney/Strength - CCET - Centre for Clean Energy Technology
utslib.copyright.status	open_access
pubs.issue	16	en_US
pubs.publication-status	Published	en_US
pubs.volume	74	en_US

Abstract:

This work provides a consistent picture of the structural, optical, and electronic properties of Fe-doped GaN. A set of high-quality GaN crystals doped with Fe at concentrations ranging from 5× 1017 cm-3 to 2× 1020 cm-3 is systematically investigated by means of electron paramagnetic resonance and various optical techniques. Fe3+ is shown to be a stable charge state at concentrations from 1× 1018 cm-3. The fine structure of its midgap states is successfully established, including an effective-mass-like state consisting of a hole bound to Fe2+ with a binding energy of 50±10 meV. A major excitation mechanism of the Fe3+ (T14 → A16) luminescence is identified to be the capture of free holes by Fe2+ centers. The holes are generated in a two-step process via the intrinsic defects involved in the yellow luminescence. The Fe3+/2+ charge-transfer level is found 2.863±0.005 eV above the valence band, suggesting that the internal reference rule does not hold for the prediction of band offsets of heterojunctions between GaN and other III-V materials. The Fe2+ (E5 → T25) transition is observed around 390 meV at any studied Fe concentration by means of Fourier transform infrared spectroscopy. Charge-transfer processes and the effective-mass-like state involving both Fe2+ states are observed. At Fe concentrations from 1× 1019 cm-3, additional lines occur in electron paramagnetic resonance and photoluminescence spectra which are attributed to defect complexes involving Fe3+. With increasing Fe concentration, the Fermi level is shown to move from near the conduction band to the Fe3+/2+ charge-transfer level, where it stays pinned for concentrations from 1× 1019 cm-3. Contrary to cubic II-VI and III-V materials, both electronic states are effected by only a weak Jahn-Teller interaction. © 2006 The American Physical Society.

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