Theory of highly excited semiconductor nanostructures including Auger coupling: Exciton-biexciton mixing in CdSe nanocrystals
Bibliographic record
Abstract
We present a theory of highly excited interacting carriers confined in a semiconductor nanostructure, incorporating Auger coupling between excited states with different number of excitations. The Coulomb matrix elements connecting exciton, biexciton, and triexciton complexes are derived and an intuitive picture of breaking neutral multiexction complexes into positively and negatively charged multiexciton complexes is given. The general approach is illustrated by analyzing the coupling of biexciton and exciton in CdSe spherical nanocrystals. The electron and hole states are computed using an atomistic $s{p}^{3}{d}^{5}{s}^{*}$ tight binding Hamiltonian including an effective crystal field splitting and surface passivation. For each number of electron-hole pairs the many-body spectrum is computed in the configuration-interaction approach. The low-energy correlated biexciton levels are broken into charged complexes: a hole and a negatively charged trion and an electron and a positively charged trion. Out of a highly excited exciton spectrum a subspace coupled to biexciton levels via Auger processes is identified. The interaction between correlated biexciton and exciton states is treated using exact diagonalization techniques. This allows to extract the spectral function of the biexciton and relate its width and amplitude to the characteristic amplitude and time scale of the coherent time evolution of the coupled system. It is shown that this process can be described by the Fermi's golden rule only if a fast relaxation of the excitonic subsystem is accounted for.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".