Although conventional homoepitaxy forms high-quality epitaxial layers1,2,3,4,5, 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 performances6,7,8, is fundamentally unavoidable in highly lattice-mismatched epitaxy9,10,11. 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.
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The data that support the findings of this study are available from the corresponding author upon reasonable request.
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This work is supported by the Defense Advanced Research Projects Agency Young Faculty Award (award no. 029584-00001), the Department of Energy Solar Energy Technologies Office (award no. DE-EE0008558), the Air Force Research Laboratory (award no. FA9453-18-2-0017), ROHM Co., and LG electronics. Y.H. and D.M. were supported by the National Science Foundation Division of Material Research (award no. 1719875). We are grateful for general support from J.S. Lee (Head of the Materials and Devices Advanced Research Institute, LG Electronics).
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Raman data, % relaxation data.
Lattice constant of InGaP on bare GaAs substrates along the x-axis and lattice constant of InGaP on graphene-coated GaAs substrates along the y-axis.
Energy barrier required for the interface sliding of epilayers on graphene/substrates and bare substrates, threshold energy for each situation and critical thickness of the heteroepitaxy film.
HRXRD azimuthal off-axis φ scan of the GaP epilayer.
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Bae, S., Lu, K., Han, Y. et al. Graphene-assisted spontaneous relaxation towards dislocation-free heteroepitaxy. Nat. Nanotechnol. 15, 272–276 (2020). https://doi.org/10.1038/s41565-020-0633-5