Geng Academic Fraud Review Report: Vapour–liquid–solid–solid growth of two-dimensional non-layered β-Bi₂O₃ crystals with high hole mobility

Academic fraud report · Geng Detector

Summary

This report applies the Geng method (五式) to evaluate the Nature Materials article (DOI: 10.1038/s41563-025-02141-w) by Xiong, Xu, Zou et al., published online 7 March 2025. Verdict: SUSPICIOUS (存疑). The review identifies four main concerns. (1) Timeline anomaly: the paper was received 2 July 2022 and accepted 15 January 2025, yielding a ~2.5-year review period, rare for Nature Materials and suggesting major revision difficulty. (2) Implausible processing robustness: the transfer protocol soaks SiO₂/Si substrates with 0.3-nm-thick non-layered β-Bi₂O₃ in 60 °C DI water for 40 min, yet the authors report a hole mobility of 136.6 cm² V⁻¹ s⁻¹ and Ra = 0.17 nm, which is physically inconsistent for an ultrathin non-layered oxide. (3) Unusual equipment choice: electron-beam lithography was performed on a TESCAN VEGA 3 teaching-grade tungsten SEM rather than a dedicated FE-EBL system, despite the report of near-ohmic contacts (1.07 kΩ μm). (4) Thermodynamic concern: directly CVD-growing a 0.3-nm non-layered tetragonal oxide on SiO₂ without passivation is questionable, since 3D islanding is favored. No image-based duplication analysis could be performed. Confidence is moderate; all claims derive from the article text and figure captions.

Verdict

Suspicious (🟡) — Multiple coherent anomalies in process description, equipment selection, and timeline warrant caution, but no decisive evidence of fabrication is presented. Pixel-level image forensics were not possible from the PDF alone.

Key findings

Prolonged review cycle (Finding 1): Received 2 July 2022; accepted 15 January 2025 — an unusually long ~2.5-year review window for Nature Materials, possibly indicating extensive revision or re-work.
Implausible water-soaking stability (Finding 2): The transfer protocol soaks samples in 60 °C DI water for 40 min. Such treatment is expected to be destructive for sub-nanometer non-layered oxide sheets, yet the authors report Ra = 0.17 nm and μ = 136.6 cm² V⁻¹ s⁻¹ afterward.
Unusual EBL instrument choice (Finding 3): EBL was carried out on a TESCAN VEGA 3 (a bench-top tungsten-filament SEM), atypical for high-mobility 2D FET fabrication yielding contact resistance as low as 1.07 kΩ μm.
Thermodynamic plausibility (Finding 4): Direct CVD growth of a 0.3-nm-thick non-layered tetragonal β-Bi₂O₃ (with c ≈ 0.56 nm) on plain SiO₂ is unlikely without passivation or strong substrate templating; 3D islanding would be favored.
Scope limitation: No image-duplication, cloning, splicing, or contrast-manipulation analysis was performed because raw high-resolution images were not available.

Evidence highlights

DOI: 10.1038/s41563-025-02141-w
Received: 2022-07-02; Accepted: 2025-01-15 (≈ 30 months).
Methods — Transfer of 2D β-Bi₂O₃: "SiO₂/Si substrates with 2D β-Bi₂O₃ were soaked in 60 °C DI water for 40 min to remove residual salt."
Reported device metrics: hole mobility 136.6 cm² V⁻¹ s⁻¹; surface roughness Ra = 0.17 nm; contact resistance 1.07 kΩ μm.
Methods — Fabrication of 2D β-Bi₂O₃ FETs: "electron-beam lithography was performed using a TESCAN VEGA 3 scanning electron microscope."
Reported film thickness: 0.3 nm, against the bulk β-Bi₂O₃ c-axis ≈ 0.56 nm.
Figure 1 (Page 689): authors acknowledge symmetry breaking in the sub-unit-cell regime.

Notes

The four findings are internally consistent in raising plausibility questions, but none individually proves data fabrication. They should be treated as reasonable hypotheses to be tested against raw data.
Recommended follow-ups: (i) verify whether mobility measurements were taken before or after the 60 °C water soak; (ii) request original HAADF-STEM images and atomic-resolution EDS for the 0.3-nm film to rule out substrate noise or contamination; (iii) track reuse of the methodology in subsequent papers from the group; (iv) post a structured query on PubPeer regarding water-soak stability and SEM-based EBL throughput.
Confidence: moderate. The timeline and the SEM-as-EBL choice are weakly indicative; the water-soak claim and the 0.3-nm non-layered oxide on bare SiO₂ are stronger red flags but remain theoretically possible under special kinetic conditions. Final judgment requires institutional investigation and inspection of the underlying raw datasets.