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 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 | 0.000 | 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 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".