Bound excitons in ZnO: Structural defect complexes versus shallow impurity centers

Wagner, MR; Callsen, G; Reparaz, JS; Schulze, JH; Kirste, R; Cobet, M; Ostapenko, IA; Rodt, S; Nenstiel, C; Kaiser, M; Hoffmann, A; Rodina, AV; Phillips, MR; Lautenschläger, S; Eisermann, S; Meyer, BK

Bound excitons in ZnO: Structural defect complexes versus shallow impurity centers

Wagner, MR Callsen, G

Reparaz, JS Schulze, JH Kirste, R Cobet, M Ostapenko, IA Rodt, S Nenstiel, C Kaiser, M Hoffmann, A Rodina, AV Phillips, MR

Lautenschläger, S Eisermann, S Meyer, BK

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Publication Type:: Journal Article
Citation:: Physical Review B - Condensed Matter and Materials Physics, 2011, 84 (3)
Issue Date:: 2011-07-11

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Field	Value	Language
dc.contributor.author	Wagner, MR	en_US
dc.contributor.author	Callsen, G https://orcid.org/0000-0001-6390-3977	en_US
dc.contributor.author	Reparaz, JS	en_US
dc.contributor.author	Schulze, JH	en_US
dc.contributor.author	Kirste, R	en_US
dc.contributor.author	Cobet, M	en_US
dc.contributor.author	Ostapenko, IA	en_US
dc.contributor.author	Rodt, S	en_US
dc.contributor.author	Nenstiel, C	en_US
dc.contributor.author	Kaiser, M	en_US
dc.contributor.author	Hoffmann, A	en_US
dc.contributor.author	Rodina, AV	en_US
dc.contributor.author	Phillips, MR https://orcid.org/0000-0003-1522-9281	en_US
dc.contributor.author	Lautenschläger, S	en_US
dc.contributor.author	Eisermann, S	en_US
dc.contributor.author	Meyer, BK	en_US
dc.date.issued	2011-07-11	en_US
dc.identifier.citation	Physical Review B - Condensed Matter and Materials Physics, 2011, 84 (3)	en_US
dc.identifier.issn	1098-0121	en_US
dc.identifier.uri	http://hdl.handle.net/10453/17997
dc.description.abstract	ZnO single crystals, epilayers, and nanostructures often exhibit a variety of narrow emission lines in the spectral range between 3.33 and 3.35 eV which are commonly attributed to deeply bound excitons (Y lines). In this work, we present a comprehensive study of the properties of the deeply bound excitons with particular focus on the Y0 transition at 3.333 eV. The electronic and optical properties of these centers are compared to those of the shallow impurity related exciton binding centers (I lines). In contrast to the shallow donors in ZnO, the deeply bound exciton complexes exhibit a large discrepancy between the thermal activation energy and localization energy of the excitons and cannot be described by an effective mass approach. The different properties between the shallow and deeply bound excitons are also reflected by an exceptionally small coupling of the deep centers to the lattice phonons and a small splitting between their two electron satellite transitions. Based on a multitude of different experimental results including magnetophotoluminescence, magnetoabsorption, excitation spectroscopy (PLE), time resolved photoluminescence (TRPL), and uniaxial pressure measurements, a qualitative defect model is developed which explains all Y lines as radiative recombinations of excitons bound to extended structural defect complexes. These defect complexes introduce additional donor states in ZnO. Furthermore, the spatially localized character of the defect centers is visualized in contrast to the homogeneous distribution of shallow impurity centers by monochromatic cathodoluminescence imaging. A possible relation between the defect bound excitons and the green luminescence band in ZnO is discussed. The optical properties of the defect transitions are compared to similar luminescence lines related to defect and dislocation bound excitons in other II-VI and III-V semiconductors. © 2011 American Physical Society.	en_US
dc.relation.ispartof	Physical Review B - Condensed Matter and Materials Physics	en_US
dc.relation.isbasedon	10.1103/PhysRevB.84.035313	en_US
dc.subject.classification	Fluids & Plasmas	en_US
dc.title	Bound excitons in ZnO: Structural defect complexes versus shallow impurity centers	en_US
dc.type	Journal Article
utslib.citation.volume	3	en_US
utslib.citation.volume	84	en_US
utslib.for	0204 Condensed Matter Physics	en_US
utslib.for	0303 Macromolecular and Materials Chemistry	en_US
utslib.for	0306 Physical Chemistry (incl. Structural)	en_US
utslib.for	02 Physical Sciences	en_US
utslib.for	03 Chemical Sciences	en_US
utslib.for	09 Engineering	en_US
dc.location.activity	WOS:000293129200009	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	closed_access
pubs.issue	3	en_US
pubs.publication-status	Published	en_US
pubs.volume	84	en_US

Abstract:

ZnO single crystals, epilayers, and nanostructures often exhibit a variety of narrow emission lines in the spectral range between 3.33 and 3.35 eV which are commonly attributed to deeply bound excitons (Y lines). In this work, we present a comprehensive study of the properties of the deeply bound excitons with particular focus on the Y0 transition at 3.333 eV. The electronic and optical properties of these centers are compared to those of the shallow impurity related exciton binding centers (I lines). In contrast to the shallow donors in ZnO, the deeply bound exciton complexes exhibit a large discrepancy between the thermal activation energy and localization energy of the excitons and cannot be described by an effective mass approach. The different properties between the shallow and deeply bound excitons are also reflected by an exceptionally small coupling of the deep centers to the lattice phonons and a small splitting between their two electron satellite transitions. Based on a multitude of different experimental results including magnetophotoluminescence, magnetoabsorption, excitation spectroscopy (PLE), time resolved photoluminescence (TRPL), and uniaxial pressure measurements, a qualitative defect model is developed which explains all Y lines as radiative recombinations of excitons bound to extended structural defect complexes. These defect complexes introduce additional donor states in ZnO. Furthermore, the spatially localized character of the defect centers is visualized in contrast to the homogeneous distribution of shallow impurity centers by monochromatic cathodoluminescence imaging. A possible relation between the defect bound excitons and the green luminescence band in ZnO is discussed. The optical properties of the defect transitions are compared to similar luminescence lines related to defect and dislocation bound excitons in other II-VI and III-V semiconductors. © 2011 American Physical Society.

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