Systematic spatial and stoichiometric screening towards understanding the surface of ultrasmall oxygenated silicon nanocrystal
| Autor: | Emmanuel N. Koukaras, Imran Sadiq, Oǧuz Gülseren, Shanawer Niaz, Aristides D. Zdetsis |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Lowest unoccupied molecular orbital
Binding energy Ab initio DFT calculation General Physics and Astronomy 02 engineering and technology DFT calculations 01 natural sciences Oxygen Computational chemistry Semiconductor quantum dots HOMO/LUMO Highest occupied molecular orbital Quantum dots Chemical bonds Surfaces and Interfaces 021001 nanoscience & nanotechnology Condensed Matter Physics Stoichiometry Nanocrystals Surfaces Coatings and Films Hydrogen-terminated silicon Chemical physics Electronic properties Molecular orbitals Density functional theory 0210 nano-technology Oxygenated dots Silicon Materials science Bins FOS: Physical sciences chemistry.chemical_element 010402 general chemistry Atomic orbital Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Spatial distribution Condensed Matter - Mesoscale and Nanoscale Physics General Chemistry 0104 chemical sciences Optical waveguides chemistry Nanocrystal Quantum dot Silicon nanocrystals Representative case Model calculations Calculations |
| Zdroj: | Applied Surface Science |
| Popis: | In most of the realistic ab initio and model calculations which have appeared on the emission of light from Si 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 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 and trends. It is also demonstrated that oxidizing constituent besides their spatial distribution significantly alters binding energy and highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) gap (HOMO-LUMO gap up to 1.48 eV) within same composition. 21 pages, 6 figures, 1 table |
| Databáze: | OpenAIRE |
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