Graphene-assisted spontaneous relaxation towards dislocation-free heteroepitaxy


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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Fig. 1: Strain analysis by Raman spectra and schematic images.
Fig. 2: Cross-sectional ADF-STEM images of InGaP grown on bare GaAs and graphene/GaAs.
Fig. 3: Theoretical calculation to understand spontaneous relaxation.
Fig. 4: Highly mismatched system of GaP on GaAs.

Data availability

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).

Author information




J.K., S.-H.B., K. Lu, Y.H., S.K. and K. Lee conceived the experiment. S.-H.B., K. Lu and H.K. contributed to the epitaxial growth. S.-H.B., K. Lu, B.-S.K., C.K. and J.S. worked on the graphene transfer. Y.H. and S.K. performed the TEM. S.-H.B., K. Lu, Y.H., S.K., D.A.M., K. Lee and J.K. analysed the TEM data. K.Q., W.K. and Y.B. analysed the Raman spectra. C.C. and Y.N. designed and performed the DFT calculation. B.-S.K. and J.L. contributed to the modelling data summary and figure configuration. K. Lu, H.S.K. and P.C. performed XRD. K. Lu and H.K. carried out the EBSD measurement. S.-H.B., K.Q., J.P., M.J. and J.K. contributed to the strain relaxation analysis. All the authors contributed to the discussion and analysis of the results regarding the manuscript. J.K. directed the team.

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Correspondence to Kyusang Lee or Jeehwan Kim.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–11, discussion.

Source data

Source Data Fig. 1

Raman data, % relaxation data.

Source Data Fig. 2

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.

Source Data Fig. 3

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.

Source Data Fig. 4

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).

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