A Probe of Valence and Conduction Band Electronic Structure of Lead Oxide Films for Photodetectors
Bibliographic record
Abstract
We investigate how the electronic structure of amorphous lead oxide (a-PbO) films deposited on ITO substrate is changed after annealing at various temperatures. Both experimental soft X-ray spectroscopic and density functional theory (DFT) based computational techniques are used to explore the electronic structure of this material. X-ray emission, resonant X-ray inelastic scattering, and X-ray absorption spectroscopic techniques are employed to directly probe the valence and conduction bands. We discover that the films are very stable and remain amorphous when exposed to temperatures below 300 °C. An amorphous-to-polycrystalline (α-PbO phase) transformation occurs during annealing at 400 °C. At 500 °C, an alpha to beta phase change is observed. These structural modifications are accompanied by the band gap value changing from 1.4±0.2 eV to 2.0±0.2 eV upon annealing at 400 °C and to 2.6±0.2 eV upon annealing at 500 °C. A difference between surface and bulk structural properties is found for all samples annealed at 500 °C and above; these samples also exhibit an unexpected suppression of O : 2p density of states (DOS) near the bottom of the conduction band, whereas additional electronic states appear well within the valence band. This study provides a significant step forward to understanding the electronic properties of two polymorphic forms of PbO needed for optimization of this material for use in X-ray sensors.
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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) | 0.001 | 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".