Characterization and field emission properties of lanthanum monosulfide nanoprotrusion arrays obtained by pulsed laser deposition on self-assembled nanoporous alumina templates
Bibliographic record
Abstract
Three distinct types of nanostructures—nanodomes, nanodots, and nanowires—have been simultaneously self-assembled by pulsed laser deposition of lanthanum monosulfide on anodic alumina films containing hexagonal arrays of pores about 50nm wide and 500nm deep. The nanostructures have been characterized by x-ray diffraction, atomic force microscopy (AFM), and field emission scanning electron microscopy (FE-SEM). Nanodomes preferentially grow on the boundary separating regions (grains) of the alumina template that have near perfect pore ordering, and their density is ∼109∕cm2. The diameter of a nanodome at the base is about 100nm and their aspect ratio (height/diameter at the base) is between 1 and 3. Additionally, nanodots nucleate on top of the alumina walls that separate adjacent pores. They have a diameter of ∼50nm, a density equal to the pore density (1010∕cm2), and an aspect ratio less than 1. Finally, cross sectional FE-SEM images of the templates indicate that LaS nanowires grow inside the pores with a density of 1010∕cm2. They have a diameter of 50nm and a maximum length equal to the length of the pores (∼500nm). The field emission properties of the LaS nanodomes and nanodots have been analyzed via the scanning anode field emission microscopy technique (SAFEM). For a fixed SAFEM probe to cathode distance, the applied voltage necessary to extract the same FE current is found to be ∼3.5 times less for a LaS thin film deposited on alumina templates compared to the value recorded for LaS thin films deposited on Silicon substrates. Assuming a LaS work function of ∼1eV (as recorded for LaS thin films grown on silicon substrates), a field enhancement factor of ∼5.8 is extracted for the nanoscale emitters from Fowler-Nordheim plots of the FE data. The field enhancement effect accrues from the concentration of electric field lines at the tip of the nanodome and nanodot emitters. The value of 5.8 can be correlated to an aspect ratio of 2.7 for the dominant emitter, which is in good agreement with the aspect ratio of the tallest nanodomes observed in AFM measurements.
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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) | 0.000 | 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 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".