Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Two-dimensional gallium nitride realized via graphene encapsulation


The spectrum of two-dimensional (2D) and layered materials ‘beyond graphene’ offers a remarkable platform to study new phenomena in condensed matter physics. Among these materials, layered hexagonal boron nitride (hBN), with its wide bandgap energy (5.0–6.0 eV), has clearly established that 2D nitrides are key to advancing 2D devices1. A gap, however, remains between the theoretical prediction of 2D nitrides ‘beyond hBN’2,3 and experimental realization of such structures. Here we demonstrate the synthesis of 2D gallium nitride (GaN) via a migration-enhanced encapsulated growth (MEEG) technique utilizing epitaxial graphene. We theoretically predict and experimentally validate that the atomic structure of 2D GaN grown via MEEG is notably different from reported theory2,3,4. Moreover, we establish that graphene plays a critical role in stabilizing the direct-bandgap (nearly 5.0 eV), 2D buckled structure. Our results provide a foundation for discovery and stabilization of 2D nitrides that are difficult to prepare via traditional synthesis.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Properties of 2D nitrides from ab initio hybrid density functional theory.
Figure 2: 2D GaN formation via migration-enhanced encapsulated growth (MEEG).
Figure 3: Pathways for intercalation and structure of 2D GaN.
Figure 4: Role of graphene in the atomic stabilization of 2D nitrides.
Figure 5: Density of state (DOS) calculations, bandgap (Eg) and electrical measurements of 2D GaN.

Similar content being viewed by others


  1. Watanabe, K., Taniguchi, T. & Kanda, H. Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal. Nat. Mater. 3, 404–409 (2004).

    Article  CAS  Google Scholar 

  2. Zhuang, H. L., Singh, A. K. & Hennig, R. G. Computational discovery of single-layer III-V materials. Phys. Rev. B 87, 165415 (2013).

    Article  Google Scholar 

  3. Singh, A. K., Zhuang, H. L. & Hennig, R. G. Ab initio synthesis of single-layer III-V materials. Phys. Rev. B 89, 245431 (2014).

    Article  Google Scholar 

  4. Singh, A. K. & Hennig, R. G. Computational synthesis of single-layer GaN on refractory materials. Appl. Phys. Lett. 105, 051604 (2014).

    Article  Google Scholar 

  5. Simon, J. et al. Polarization-induced Zener tunnel junctions in wide-band-gap heterostructures. Phys. Rev. Lett. 103, 026801 (2009).

    Article  Google Scholar 

  6. Kako, S. et al. A gallium nitride single-photon source operating at 200 K. Nat. Mater. 5, 887–892 (2006).

    Article  CAS  Google Scholar 

  7. Miao, M. S. et al. Polarization-driven topological insulator transition in a GaN/InN/GaN quantum well. Phys. Rev. Lett. 109, 186803 (2012).

    Article  CAS  Google Scholar 

  8. Freeman, C. L., Claeyssens, F., Allan, N. L. & Harding, J. H. Graphitic nanofilms as precursors to wurtzite films: theory. Phys. Rev. Lett. 96, 066102 (2006).

    Article  Google Scholar 

  9. Brus, L. E. Electron–electron and electron-hole interactions in small semiconductor crystallites: The size dependence of the lowest excited electronic state. J. Chem. Phys. 80, 4403–4409 (1984).

    Article  CAS  Google Scholar 

  10. Tsipas, P. et al. Evidence for graphite-like hexagonal AlN nanosheets epitaxially grown on single crystal Ag(111). Appl. Phys. Lett. 103, 251605 (2013).

    Article  Google Scholar 

  11. Bhattacharya, S., Datta, A., Dhara, S. & Chakravorty, D. Growth of two-dimensional GaN in Na-4 mica nanochannels. J. Phys. D 42, 235504 (2009).

    Google Scholar 

  12. Tasker, P. W. The stability of ionic crystal surfaces. J. Phys. C 12, 4984 (1979).

    Article  Google Scholar 

  13. Noguera, C. Polar oxide surfaces. J. Phys. Condens. Matter 12, R367 (2000).

    Article  CAS  Google Scholar 

  14. Li, J. & Wang, L.-W. Band-structure-corrected local density approximation study of semiconductor quantum dots and wires. Phys. Rev. B 72, 125325 (2005).

    Article  Google Scholar 

  15. Emtsev, K. V. et al. Towards wafer-size graphene layers by atmospheric pressure graphitization of silicon carbide. Nat. Mater. 8, 203–207 (2009).

    Article  CAS  Google Scholar 

  16. Riedl, C., Coletti, C., Iwasaki, T., Zakharov, A. A. & Starke, U. Quasi-free-standing epitaxial graphene on SiC obtained by hydrogen intercalation. Phys. Rev. Lett. 103, 246804 (2009).

    Article  CAS  Google Scholar 

  17. Wang, Z. et al. Simultaneous N-intercalation and N-doping of epitaxial graphene on 6H-SiC(0001) through thermal reactions with ammonia. Nano Res. 6, 399–408 (2013).

    CAS  Google Scholar 

  18. Virojanadara, C., Watcharinyanon, S., Zakharov, A. A. & Johansson, L. I. Epitaxial graphene on 6H-SiC and Li intercalation. Phys. Rev. B 82, 205402 (2010).

    Article  Google Scholar 

  19. Schumacher, S. et al. Europium underneath graphene on Ir(111): intercalation mechanism, magnetism, and band structure. Phys. Rev. B 90, 235437 (2014).

    Article  Google Scholar 

  20. Petrović, M. et al. The mechanism of caesium intercalation of graphene. Nat. Commun. 4, 2772 (2013).

    Article  Google Scholar 

  21. Al Balushi, Z. Y. et al. The impact of graphene properties on GaN and AlN nucleation. Surf. Sci. 634, 81–88 (2015).

    Article  CAS  Google Scholar 

  22. Boukhvalov, D. W. & Katsnelson, M. I. Destruction of graphene by metal adatoms. Appl. Phys. Lett. 95, 023109 (2009).

    Article  Google Scholar 

  23. Sun, G. F., Jia, J. F., Xue, Q. K. & Li, L. Atomic-scale imaging and manipulation of ridges on epitaxial graphene on 6H-SiC(0001). Nanotechnology 20, 355701 (2009).

    Article  CAS  Google Scholar 

  24. Alaskar, Y. et al. Towards van der Waals epitaxial growth of GaAs on Si using a graphene buffer layer. Adv. Funct. Mater. 24, 6629–6638 (2014).

    Article  CAS  Google Scholar 

  25. Huang, W., Gan, L., Li, H., Ma, Y. & Zhai, T. 2D layered group IIIA metal chalcogenides: synthesis, properties and applications in electronics and optoelectronics. Cryst. Eng. Comm. 18, 3968–3984 (2016).

    Article  CAS  Google Scholar 

  26. Findlay, S. D. et al. Robust atomic resolution imaging of light elements using scanning transmission electron microscopy. Appl. Phys. Lett. 95, 191913 (2009).

    Article  Google Scholar 

  27. Northrup, J. E., Neugebauer, J., Feenstra, R. M. & Smith, A. R. Structure of GaN(0001): the laterally contracted Ga bilayer model. Phys. Rev. B 61, 9932–9935 (2000).

    Article  CAS  Google Scholar 

  28. Espitia-Rico, M., Rodríguez-Martínez, J. A., Moreno-Armenta, M. G. & Takeuchi, N. Graphene monolayers on GaN(0001). Appl. Surf. Sci. 326, 7–11 (2015).

    Article  CAS  Google Scholar 

  29. Caffrey, N. M., Armiento, R., Yakimova, R. & Abrikosov, I. A. Charge neutrality in epitaxial graphene on 6H-SiC(0001) via nitrogen intercalation. Phys. Rev. B 92, 081409 (2015).

    Article  Google Scholar 

  30. Caldwell, J. D. et al. Atomic-scale photonic hybrids for mid-infrared and terahertz nanophotonics. Nat. Nanotech. 11, 9–15 (2016).

    Article  CAS  Google Scholar 

Download references


Materials and experimental methods in this work were partially supported by Asahi Glass Japan and the National Science Foundation under grant numbers DMR-1006763 (J.M.R.), DMR-1410765 (J.M.R.), DMR-1420620 (J.M.R & J.A.R Seed Program through Penn State MRSEC—Center for Nanoscale Science) and DMR-1453924 (J.A.R.). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Material characterization described in this work was supported by The Pennsylvania State University (PSU) Materials Characterization Laboratory (MCL) Staff Innovation Funding (SIF) Program, and the Alfred P. Sloan Foundation, USA. Theoretical work (S.D.) and XPS analysis (R.M.W.) was supported by the Center for Low Energy Systems Technology (LEAST). LEAST is one of six Semiconductor Research Corporation STARnet centres sponsored by MARCO and DARPA. We would like acknowledge V. Bojan (staff scientist, MCL) and J. Maier (technical staff, MCL) for contributions in AES analysis and FIB-TEM specimen preparation, respectively. In addition, we also acknowledge the microscopy and spectroscopy assistance provided by: N. Alem (PSU); K. Bernd (PSU); A. Azizi (PSU); J. Tischler (NRL); C. Ellis (NRL); J. Owrutsky (NRL) and T. Miyagi (Asahi Glass, Japan). Finally, we thank T. Tiwald (J.A. Woolam) for his assistance in developing the ellipsometric model with J.D.C. and P. Sheehan (NRL) for his beneficence in allowing us to use his ellipsometer.

Author information

Authors and Affiliations



Experiments were designed by Z.Y.A., J.M.R. and J.A.R. The MEEG process development, SEM, Raman and data analysis (electrical, microscopic and spectroscopic) were performed by Z.Y.A. High-resolution electron microscopy was conducted by K.W. and ABF-STEM simulations by G.S. Moreover, R.K.G. and S.D. designed and implemented theoretical calculations and structure simulations. R.A.V., S.M.E. and S.S. carried out epitaxial graphene growth and quality assessment. UV-Vis measurements were performed at NRL by P.A.D. and J.D.C.; J.D.C. also performed ellipsometric measurements and model development. X.Q. and R.M.W. performed the plasma processing, XPS measurements and analysis at UT Dallas. Y.-C.L. performed vertical transport measurements using C-AFM and S.D. provided input on IV characteristics. Finally, D.F.P. performed AES measurements at PHI. All authors discussed results at all stages. Z.Y.A., J.A.R. and J.M.R. wrote the paper.

Corresponding authors

Correspondence to Joan M. Redwing or Joshua A. Robinson.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 1392 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Al Balushi, Z., Wang, K., Ghosh, R. et al. Two-dimensional gallium nitride realized via graphene encapsulation. Nature Mater 15, 1166–1171 (2016).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing