Systematic spatial and stoichiometric screening towards understanding the surface of ultrasmall oxygenated silicon nanocrystal
Author
Niaz, S.
Zdetsis, A. D.
Koukaras, E. N.
Gülseren, O.
Sadiq, I.
Date
2016-11Source Title
Applied Surface Science
Print ISSN
0169-4332
Publisher
Elsevier
Volume
387
Pages
771 - 778
Language
English
Type
ArticleItem Usage Stats
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Show full item recordAbstract
In most of the realistic ab initio and model calculations which have appeared on the emission of light from silicon nanocrystals, the role of surface oxygen has been usually ignored, underestimated or completely ruled out. We investigate theoretically, by density functional theory (DFT/B3LYP) possible modes of oxygen bonding in hydrogen terminated silicon quantum dots using as a representative case of the Si29 nanocrystal. We have considered Bridge-bonded oxygen (BBO), Doubly-bonded oxygen (DBO), hydroxyl (OH) and Mix of these oxidizing agents. Due to stoichiometry, all comparisons performed are unbiased with respect to composition whereas spatial distribution of oxygen species pointed out drastic change in electronic and cohesive characteristics of nanocrytals. From an overall perspective of this study, it is shown that bridge bonded oxygenated Si nanocrystals accompanied by Mix have higher binding energies and large electronic gap compared to nanocrystals with doubly bonded oxygen atoms. In addition, it is observed that the presence of OH along with BBO, DBO and mixed configurations further lowers electronic gaps and binding energies but trends in same fashion. It is also demonstrated that within same composition, oxidizing constituent, along with their spatial distribution substantially alters binding energy, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) gap (up to 1.48 eV) and localization of frontier orbitals.
Keywords
DFT calculationsElectronic properties
Oxygenated dots
Quantum dots
Silicon nanocrystals
Stoichiometry
Binding energy
Bins
Calculations
Chemical bonds
Density functional theory
Electronic properties
Molecular orbitals
Optical waveguides
Oxygen
Semiconductor quantum dots
Silicon
Spatial distribution
Stoichiometry
DFT calculation
Highest occupied molecular orbital
Hydrogen-terminated silicon
Lowest unoccupied molecular orbital
Model calculations
Oxygenated dots
Representative case
Silicon nanocrystals
Nanocrystals
Permalink
http://hdl.handle.net/11693/36876Published Version (Please cite this version)
https://doi.org/10.1016/j.apsusc.2016.06.197Collections
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