Evidence of air-induced surface transformation of atomic step-engineered sapphire in relation to epitaxial growth of 2D semiconductors
Engineering sapphire substrates with specific surface characteristics is crucial for the epitaxial growth of high-quality wafer-scale transition metal dichalcogenides, essential for integration with semiconductor industry processes. Here, we report that atomic-step-engineered sapphire surfaces undergo structural and chemical changes upon air exposure, which may be associated with surface hydrolysis and the formation of aluminum (oxy)hydroxides as revealed by a self-developed charge-contrast enhanced X-ray photoelectron spectroscopy technique. We suggest these species transform into oxygen-deficient Al<sub>2</sub>O<sub>3-x</sub> under typical growth conditions, associated with disrupted domain alignment. We further demonstrate that ultraviolet light irradiation in air appears to mitigate this degradation, restoring surface stoichiometry and promoting epitaxial alignment. The grown monolayer WS₂ films exhibit high crystalline quality, good uniformity, and low defect density. Statistical analysis of 100 field-effect transistors shows a device yield >95% and a mobility variation <20%. These findings provide relevant insights for the consistent production of industrial-scale, high-quality 2D semiconductors.
Authors
- Siew Lang Teo (ORCID: https://orcid.org/0000-0001-8938-2495)
- Thathsara D. Maddumapatabandi (ORCID: https://orcid.org/0000-0002-5768-2423)
- Michel Bosman (ORCID: https://orcid.org/0000-0002-8717-7655)
- Chit Siong Lau (ORCID: https://orcid.org/0000-0002-6590-070X)
- Ding Huang (ORCID: https://orcid.org/0000-0002-1588-4967)
- Henry Medina (ORCID: https://orcid.org/0000-0003-1461-5703)
- Calvin Pei Yu Wong (ORCID: https://orcid.org/0000-0002-3135-7534)
- Ming Lin (ORCID: https://orcid.org/0000-0001-5284-6591)
- Hiroyo Kawai (ORCID: https://orcid.org/0000-0003-1197-7178)
- Yunjie Chen (ORCID: https://orcid.org/0000-0002-3210-6366)
- Wei Fu (ORCID: https://orcid.org/0000-0001-5018-1960)
- Kuan Eng Johnson Goh (ORCID: https://orcid.org/0000-0003-0599-9696)
- Fabio Bussolotti (ORCID: https://orcid.org/0000-0001-8725-4545)
- Rainer Lee
- Anqi Sng (ORCID: https://orcid.org/0009-0004-5876-5329)
- Mingsheng Zhang (ORCID: https://orcid.org/0000-0001-7516-3507)
- Hui Ru Tan (ORCID: https://orcid.org/0000-0003-4839-4515)
- Jianwei Chai (ORCID: https://orcid.org/0009-0006-8037-4089)
Institutions
- Centre for Quantum Technologies (SG)
- Singapore University of Technology and Design (SG)
- National University of Singapore (SG)
- Nanyang Technological University (SG)
- Institute of High Performance Computing (SG)
- IMEC (BE)
- Institute of Materials Research and Engineering (SG)
Publication Details
- Journal
- Nature Communications
- Published
- 2025-09-26
- DOI
- https://doi.org/10.1038/s41467-025-63452-9
- Citations
- 3
- Primary Topic
- Nanowire Synthesis and Applications
- Type
- article
- Field-Weighted Citation Impact
- 2.02
Funders
- National Research Foundation
- Agency for Science, Technology and Research
- National Research Foundation Singapore
- Ministry of Education - Singapore
- Ministry of Education, India
- Centre for Quantum Technologies