Graphene-assisted spontaneous relaxation towards dislocation-free heteroepitaxy

• Published in: Nature nanotechnology Vol. 15; no. 4; pp. 272 - 276
• Main Authors: Bae, Sang-Hoon, Lu, Kuangye, Han, Yimo, Kim, Sungkyu, Qiao, Kuan, Choi, Chanyeol, Nie, Yifan, Kim, Hyunseok, Kum, Hyun S., Chen, Peng, Kong, Wei, Kang, Beom-Seok, Kim, Chansoo, Lee, Jaeyong, Baek, Yongmin, Shim, Jaewoo, Park, Jinhee, Joo, Minho, Muller, David A., Lee, Kyusang, Kim, Jeehwan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.04.2020; Nature Publishing Group
• Subjects: 140/133; 639/301/357/918; 639/925/357; Chemistry and Materials Science; Crystal dislocations; Crystal structure; Crystallinity; Dislocation; Dislocation density; Electronic devices; Film thickness; Graphene; Letter; Materials Science; NANOSCIENCE AND NANOTECHNOLOGY; Nanotechnology; Nanotechnology and Microengineering; Photonics; Semiconductor devices; Single crystals; Substrates
• ISSN: 1748-3387; 1748-3395
• DOI: 10.1038/s41565-020-0633-5

Although conventional homoepitaxy forms high-quality epitaxial layers 1 – 5 , the limited set of material systems for commercially available wafers restricts the range of materials that can be grown homoepitaxially. At the same time, conventional heteroepitaxy of lattice-mismatched systems produces dislocations above a critical strain energy to release the accumulated strain energy as the film thickness increases. The formation of dislocations, which severely degrade electronic/photonic device performances 6 – 8 , is fundamentally unavoidable in highly lattice-mismatched epitaxy 9 – 11 . Here, we introduce a unique mechanism of relaxing misfit strain in heteroepitaxial films that can enable effective lattice engineering. We have observed that heteroepitaxy on graphene-coated substrates allows for spontaneous relaxation of misfit strain owing to the slippery graphene surface while achieving single-crystalline films by reading the atomic potential from the substrate. This spontaneous relaxation technique could transform the monolithic integration of largely lattice-mismatched systems by covering a wide range of the misfit spectrum to enhance and broaden the functionality of semiconductor devices for advanced electronics and photonics. The spontaneous relaxation of misfit strain achieved on graphene-coated substrates enables the growth of heteroepitaxial single-crystalline films with reduced dislocation density.