Electronic structure study of ion-implanted Si quantum dots in a SiO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow/><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>matrix: Analysis of quantum confinement theories
Bibliographic record
Abstract
The electronic states and optical properties of Si quantum dots (QDs) with variable size prepared by ion implantation in a SiO${}_{2}$ matrix are studied by x-ray photoemission spectroscopy (XPS), photoluminescence (PL), and Raman spectroscopy. The results are compared with several theories of quantum confinement. Our Si 2$p$ binding energies and the valence band energies do not change as a function of QD diameter nor compared to the bulk Si values. Raman spectra show no signs of stress on the Si-QDs. XPS data indicates the presence of a Si${}_{2}$O${}_{3}$ interfacial layer between the Si-QDs and the surrounding SiO${}_{2}$ matrix, which is understood to relieve stress in the QDs and to cause pinning of the valence level. Our XPS results for ion-beam implanted QDs are compared with other group's studies for Si-QDs prepared by alternative methods, and discrepancies in the interfacial compositions are discussed. These results call into question the fundamental predictions and assumptions of many quantum confinement models. It is concluded that the lack of a shift in the valence band is due to a symmetry-breaking process in the hole states, which is not currently accounted for by theory, demonstrating the importance of the hole states during radiative events. This work is intended as a first step in highlighting the features that should be present in a theoretical formalism for embedded Si-QDs, and cause is given to abandon particular formalisms.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".