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On the Location of Boron in SiO2‐embedded Si Nanocrystals – An X‐ray Absorption Spectroscopy and Density Functional Theory Study

Hiller, Daniel; König, Dirk; Nagel, Peter 1; Merz, Michael 1; Schuppler, Stefan 1; Smith, Sean C.
1 Institut für Quantenmaterialien und -technologien (IQMT), Karlsruher Institut für Technologie (KIT)

Doping of silicon nanostructures is crucial to understand their properties and to enhance their potential in various fields of application. Herein, SiO2-embedded Si nanocrystals (quantum dots) ≈3–6 nm in diameter are used as a model system to study the incorporation of B dopants by X-ray absorption near-edge spectroscopy (XANES). Such samples represent a model system for ultimately scaled, 3D-confined Si nanovolumes. The analysis is complemented by real-space density functional theory to calculate the 1s (K shell) electron binding energies of B in 11 different, thermodynamically stable configurations of the Si/SiOx/SiO2 system. Although no indications for a substitutional B-acceptor configuration are found, the predominant O coordination of B indicates the preferred B incorporation into the SiO2 matrix and near the Si-nanocrystal/SiO2 interface, which is inherently incompatible with charge carrier generation by dopants. It is concluded that B doping of ultrasmall Si nanostructures fails due to a lack of B incorporation onto Si lattice sites that cannot be overcome by increasing the B concentration. The inability to efficiently insert B into Si nanovolumes appears to be a boron-specific fundamental obstacle for electronic doping (e.g., not observed for phosphorus) that adds to the established nanosize effects, namely, increased dopant activation and ionization energies.

Verlagsausgabe §
DOI: 10.5445/IR/1000131698
Veröffentlicht am 29.06.2021
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Quantenmaterialien und -technologien (IQMT)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 04.2021
Sprache Englisch
Identifikator ISSN: 0370-1972, 1521-3951
KITopen-ID: 1000131698
HGF-Programm 47.11.02 (POF IV, LK 01) Emergent Quantum Phenomena
Weitere HGF-Programme 43.21.01 (POF III, LK 01) Quantum Correlations in Condensed Matter
Erschienen in Physica status solidi / B
Verlag John Wiley and Sons
Band 258
Heft 7
Seiten Art.-Nr. 2000623
Vorab online veröffentlicht am 24.03.2021
Schlagwörter KNMF 2017-017-016949 WERA
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