Diffusion and recombination of optically-injected carriers in a semiconductor wafer in 3-dimensions
Bibliographic record
Abstract
In this work, we derive a general equation describing the transmission of a probe beam in a pump/probe experiment upon optical injection of carriers into a semiconductor. The pump/probe radial overlap equation generalizes previous pump/probe approaches by considering the pump and probe beam sizes relative to each other and to the diffusion length. The pump/probe equation leverages a powerful solution to the free-carrier density under optical injection that is also derived in this work. The free-carrier density solution extends the work of Luke and Cheng to 3-dimensions, incorporating the effects of radial diffusion in a plane parallel to the semiconductor surface. The pump/probe equation quantifies the magnitude of free-carrier absorption of a probe beam induced by free-carriers optically injected via a pump beam. We show that when the pump/probe beams are much smaller than the carrier diffusion length, radial diffusion effects dominate. Measurements in this regime can be used to uniquely and simultaneously determine both the effective carrier lifetime and the diffusion coefficient. The equation agrees well with experimental measurements using a recently developed single-beam pump/probe technique, which ensures a perfect overlap of the pump and probe beams. Based on this equation, measurement criteria are developed for accurate determination of carrier lifetime and to correct for the effects of radial diffusion.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".