Pressure-Driven Metallicity in Ångström-Thickness 2D Bismuth and Layer-Selective Ohmic Contact to MoS<sub>2</sub>
Bibliographic record
Abstract
Recent fabrication of two-dimensional (2D) metallic bismuth (Bi) via van der Waals (vdW) squeezing offers a route to ultrascaling metal into ångström thickness. However, free-standing 2D Bi is typically semiconducting, which contradicts the experimentally observed metallicity in vdW-squeezed 2D Bi. Here we show that this discrepancy originates from the pressure-induced buckled-to-flat structural transition in 2D Bi, changing the electronic structures from semiconducting to semimetallic. Based on the experimentally fabricated MoS 2 -Bi-MoS 2 trilayer heterostructure, we demonstrate the concept of layer-selective Ohmic contact in which one MoS 2 layer forms an Ohmic contact to the 2D Bi while the opposite MoS 2 exhibits a Schottky barrier. The Ohmic contact can be switched between the two sandwiching MoS 2 monolayers by reversing an external gate field, thus enabling charge to be spatially injected into different MoS 2 layers. The layer-selective Ohmic contact proposed here represents a layertronic generalization of semimetal/semiconductor contact, paving the way toward layertronic device application.
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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".