Probing the Electronic Surface Properties and Bandgap Narrowing of in situ N, W, and (W,N) Doped Magnetron-Sputtered TiO<sub>2</sub> Films Intended for Electro-Photocatalytic Applications
Bibliographic record
Abstract
We report on the optical and electronic properties of undoped, nitrogen (N) doped, tungsten (W) doped, and (W,N) doped TiO 2 films deposited by RF magnetron sputtering process. The optical absorption edge of the N doped TiO 2 films is shown to red-shift significantly as compared to the undoped TiO 2 films. This tendency was found to continue with the codoped films, as their absorption edge substantially red-shifted to ∼420 nm. This red-shifting is due to the effective narrowing of the band gap of the doped films as determined via Tauc plot analysis, which confirmed a reduction of the bandgap of the (W,N) codoped TiO 2 films to a value as low as 2.2 eV (in comparison with the 3.2 eV value of the undoped TiO 2 films). From X-ray photoelectron spectroscopy (XPS) analysis, it is shown that the N and W atoms were incorporated into the O and Ti lattice sites of TiO 2 respectively. On the other hand, valence band spectra of these films suggest that it primarily consists of O 2 p derived states and the maximum upshift of surface position of valence band maximum (0.8 eV) with respect to the Fermi level was observed for (W,N) doped films, which, in turn, is in accordance with the narrowing of the bandgap revealed by UV–vis spectra analysis. Finally, by quantitatively measuring the work function of undoped, monodoped, and codoped TiO 2 films, by means of UV-photoelectron spectroscopy (UPS), we were able to achieve a complete reconstruction of their one-dimensional energy band structure. This fundamental information is highly valuable for the efficient use of doped TiO 2 films in electro-photocatalytic and/or optoelectronic applications.
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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".