Quasi-Steady-State Free Carrier Absorption Measurements of Effective Carrier Lifetime in Silicon
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Bibliographic record
Abstract
The paper presents a semiconductor carrier lifetime measurement technique, quasi-steady-state free carrier absorption (QSS-FCA), that is an all-optical analog of the quasi-steady-state photoconductivity technique. The effective electron-hole recombination lifetime of silicon is measured under quasi-steady-state conditions using an above-bandgap pump and a below-bandgap probe of the free carrier absorption (FCA). A mathematical model is developed to relate the experimentally measured probe signal to the lifetime. QSS-FCA is calibrated self-consistently by measuring the quasi-steady-state signal simultaneously with the true recombination lifetime in the same apparatus. This directly establishes the relationship between the quasi-steady-state signal and lifetime, ensuring the accuracy of QSS-FCA measurements. The calibration constant is the FCA cross section of silicon, which is a material constant. QSS-FCA is a simplification of traditional FCA lifetime measurement approaches where the lifetime is extracted from a time- or frequency-resolved carrier decay. Both of these approaches require a bandwidth commensurate with the inverse carrier lifetime of the wafer and require fitting multiple data points in order to extract the lifetime. In contrast, QSS-FCA is a quasi-steady-state measurement, so it is inherently low frequency, and as a single point measurement technique, fitting is not required. Finally, since QSS-FCA is a purely optical technique, it opens up the possibility of in situ lifetime characterization that would be inaccessible to the traditional RF/microwave-based lifetime measurement techniques.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.000 | 0.000 |
Machine scores (provisional)
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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 it