Electronic Transport in Tin(IV) Oxide Nanocrystalline Films: Two-Medium Transport with Three-Dimensional Variable-Range Hopping Mechanism for the Ultrasmall Nanocrystallite Size Regime
Bibliographic record
Abstract
Homogeneous, nanocrystalline films of tin(IV) oxide with controllable crystalline grains in the ultrasmall size range of 4–12 nm have been prepared by using a simple method of spin-coating followed by annealing in oxygen at different postannealing temperatures ( T anneal ). These nanocrystalline films all exhibit a high optical transparency of 90–100% in the visible region with a band gap of 3.71 ± 0.05–3.87 ± 0.05 eV compared to 3.6 eV for bulk SnO 2, indicating a high carrier density for all the TO films. The films obtained with T anneal ≥ 350 °C, marking the onset of crystallization, are found to be conductive. The ac resistivity is measured as a function of temperature between 50 and 280 K for all the conductive films, and two distinct behaviors are observed between 50 and 90 K (LT) and 120–280 K (HT). The presence of two different media, i.e., the crystalline grains and the charge-depletion layer, can explain the observed resistivity behavior. The excellent fit of a parallel resistor model to the resistivity data for samples obtained with T anneal = 350–700 °C further validates the presence of the two media, revealing energy barrier heights of 48.0 ± 0.4–60.5 ± 0.4 meV for transport across the grain boundaries. The resistivity behavior in each medium is best described by the three-dimensional variable-range hopping (3D-VRH) model, given its excellent fit to the experimental data. On the basis of the resistivity results as analyzed within this model, we conclude that increasing T anneal leads to a reduction in the carrier density as defect density decreases. The 3D-VRH fits to the resistivity in the LT region further reveal that above the onset of exponential growth at T anneal = 500 °C, a remarkable improvement in the charge transport occurs likely due to the observed enhanced crystallinity. Postannealing at different temperatures, therefore, has a direct effect on the extent of crystallization in the amorphous matrix and the size of the resulting nanocrystallites, both of which affect the defect density and transport channels, and can therefore be used to provide fine control on the resistivity of the nanocrystalline SnO 2 film.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".