Photonics with hexagonal boron nitride

Abstract

For more than seven decades, hexagonal boron nitride (hBN) has been employed as an inert, thermally stable engineering ceramic; since 2010, it has also been used as the optimal substrate for graphene in nanoelectronic and optoelectronic devices. Recent research has revealed that hBN exhibits a unique combination of optical properties that enable novel (nano)photonic functionalities. Specifically, hBN is a natural hyperbolic material in the mid-IR range, in which photonic material options are sparse. Furthermore, hBN hosts defects that can be engineered to obtain room-temperature, single-photon emission; exhibits strong second-order nonlinearities with broad implications for practical devices; and is a wide-bandgap semiconductor well suited for deep UV emitters and detectors. Inspired by these promising attributes, research on the properties of hBN and the development of large-area bulk and thin-film growth techniques has dramatically expanded. This Review offers a snapshot of current research exploring the properties underlying the use of hBN for future photonics functionalities and potential applications, and covers some of the remaining obstacles.

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Fig. 1: Overview of hBN-based applications.
Fig. 2: Natural hyperbolic properties of hBN in the mid-IR.
Fig. 3: Applications of hyperbolic polaritons within hBN.
Fig. 4: Room-temperature, single-photon emission in hBN.
Fig. 5: Dependence of second-harmonic generation upon hBN stacking and thickness.
Fig. 6: Phonon-assisted recombination in hBN.
Fig. 7: Methods for growing hBN.
Fig. 8: Moiré heterostructures incorporating hBN.

References

  1. 1.

    Novoselov, K. S. et al. Electric field effect in atomically thin carbon films. Science 306, 666–669 (2004).

  2. 2.

    Novoselov, K. S. et al. Two-dimensional gas of massless Dirac fermions in graphene. Nature 438, 197–200 (2005).

  3. 3.

    Zhang, Y., Tan, Y.-W., Stormer, H. L. & Kim, P. Experimental observation of the quantum Hall effect and Berry’s phase in graphene. Nature 438, 201–204 (2005).

  4. 4.

    Novoselov, K. S., Mishchenko, A., Carvalho, A. & Castro Neto, A. H. 2D materials and van der Waals heterostructures. Science 353, aac9439 (2016).

  5. 5.

    Geim, A. K. & Grigorieva, I. V. Van der Waals heterostructures. Nature 499, 419–425 (2013).

  6. 6.

    Kretinin, A. et al. Electronic properties of graphene encapsulated with different two-dimensional atomic crystals. Nano Lett. 14, 3270–3276 (2014).

  7. 7.

    Dean, C. R. et al. Boron nitride substrates for high-quality graphene electronics. Nat. Nanotechnol. 5, 722–726 (2010).

  8. 8.

    Lee, G.-H. et al. Flexible and transparent MoS2 field-effect transistors on hexagonal boron-nitride-graphene heterostructures. ACS Nano 7, 7931–7936 (2013).

  9. 9.

    Woessner, A. et al. Highly confined low-loss plasmons in graphene-boron nitride heterostructures. Nat. Mater. 14, 421–425 (2015).

  10. 10.

    Ni, G. X. et al. Fundamental limits to graphene plasmonics. Nature 557, 530–533 (2018).

  11. 11.

    Dai, S. et al. Tunable phonon polaritons in atomically thin van der Waals crystals of boron nitride. Science 343, 1125–1129 (2014).

  12. 12.

    Caldwell, J. D. et al. Sub-diffractional volume-confined polaritons in the natural hyperbolic material hexagonal boron nitride. Nat. Commun. 5, 5221 (2014).

  13. 13.

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

  14. 14.

    Dai, S. et al. Graphene on hexagonal boron nitride as a tunable hyperbolic metamaterial. Nat. Nanotechnol. 10, 682–686 (2015).

  15. 15.

    Tran, T.-T. D., Bray, V. W., Ford, M. J., Toth, M. & Aharonovich, I. Quantum emission from hexagonal boron nitride monolayers. Nat. Nanotechnol. 11, 37–41 (2016).

  16. 16.

    Cassabois, G., Valvin, P. & Gil, B. Hexagonal boron nitride is an indirect bandgap semiconductor. Nat. Photonics 10, 262–266 (2016).

  17. 17.

    Kim, C.-J. et al. Stacking order dependent second harmonic generation and topological defects in h-BN bilayers. Nano Lett. 13, 5660–5665 (2013).

  18. 18.

    Li, Y. et al. Probing symmetry properties of few-layer MoS2 and h-BN by optical second harmonic generation. Nano Lett. 13, 3329–3333 (2013).

  19. 19.

    Ni, G. X. et al. Plasmons in graphene moiré superlattices. Nat. Mater. 14, 1217–1222 (2015).

  20. 20.

    Sunku, S. S. et al. Photonic crystals for nano-light in moiré graphene superlattices. Science 362, 1153–1156 (2018).

  21. 21.

    Yu, H. Y., Liu, G. B., Tang, J. J., Xu, X. D. & Yao, W. Moiré excitons: from programmable quantum emitter arrays to spin-orbit-coupled artificial lattices. Sci. Adv. 3, e1701696 (2017).

  22. 22.

    Giles, A. J. et al. Ultra-low-loss polaritons in isotopically pure boron nitride. Nat. Mater. 17, 134–139 (2018).

  23. 23.

    Vuong, T. Q. P. et al. Isotope engineering of van der Waals interactions in hexagonal boron nitride. Nat. Mater. 17, 152–158 (2018).

  24. 24.

    Taniguchi, T. & Watanabe, K. Synthesis of high-purity boron nitride single crystals under high pressure by using Ba-BN solvent. J. Cryst. Growth 303, 525–529 (2007).

  25. 25.

    Du, X. Z., Li, J., Lin, J. Y. & Jiang, H. X. The origins of near band-edge transitions in hexagonal boron nitride epilayers. Appl. Phys. Lett. 108, 052106 (2016).

  26. 26.

    Cho, Y.-J. et al. Hexagonal boron nitride tunnel barriers grown on graphite by high temperature molecular beam epitaxy. Sci. Rep. 6, 34474 (2016).

  27. 27.

    Vuong, T. Q. P. et al. Deep ultraviolet emission in hexagonal boron nitride grown by high-temperature molecular beam epitaxy. 2D Mater. 4, 021023 (2017).

  28. 28.

    Folland, T. G., Nordin, L., Wasserman, D. & Caldwell, J. D. Probing polaritons in the mid- to far-infrared. J. Appl. Phys. 125, 191102 (2019).

  29. 29.

    Maier, S. A. Plasmonics: Fundamentals and Applications (Springer-Verlag, 2007).

  30. 30.

    Caldwell, J. D. et al. Low-loss, infrared and terahertz nanophotonics with surface phonon polaritons. Nanophotonics 4, 44–68 (2015).

  31. 31.

    Basov, D. N., Fogler, M. M. & Garcia de Abajo, F. J. Polaritons in van der Waals materials. Science 354, aag1992 (2017).

  32. 32.

    Low, T. et al. Polaritons in layered two-dimensional materials. Nat. Mater. 16, 182–194 (2017).

  33. 33.

    Xu, X. G. et al. One-dimensional surface phonon polaritons in boron nitride nanotubes. Nat. Commun. 5, 4782 (2014).

  34. 34.

    Caldwell, J. D. & Novoselov, K. S. Mid-infrared nanophotonics. Nat. Mater. 14, 364–365 (2015).

  35. 35.

    Ni, G. X. et al. Ultrafast optical switching of infrared plasmon polaritons in high-mobility graphene. Nat. Photonics 10, 244–247 (2016).

  36. 36.

    Adachi, S. Optical Properties of Crystalline and Amorphous Semiconductors: Materials and Fundamental Principles 33–61 (Springer Science+Business Media, 1999).

  37. 37.

    Poddubny, A., Iorsh, I., Belov, P. & Kivshar, Y. Hyperbolic metamaterials. Nat. Photonics 7, 948–957 (2013).

  38. 38.

    Caldwell, J. D., Vurgaftman, I. & Tischler, J. G. Probing hyperbolic polaritons. Nat. Photonics 9, 638–640 (2015).

  39. 39.

    Yoxall, E. et al. Direct observation of ultraslow hyperbolic polariton propagation with negative phase velocity. Nat. Photonics 9, 674–678 (2015).

  40. 40.

    Autore, M. et al. Boron nitride nanoresonators for phonon-enhanced molecular vibrational spectroscopy at the strong coupling limit. Light Sci. Appl. 7, 17172 (2018).

  41. 41.

    Dai, S. et al. Subdiffractional focusing and guiding of polaritonic rays in a natural hyperbolic material. Nat. Commun. 6, 6963 (2015).

  42. 42.

    Guo, Y., Newman, W., Cortes, C. L. & Jacob, Z. Applications of hyperbolic metamaterial substrates. Adv. Optoelectron. 2012, 452502 (2012).

  43. 43.

    Liu, Z., Lee, H., Xiong, Y., Sun, C. & Zhang, X. Far-field optical hyperlens magnifying sub-diffraction-limited objects. Science 315, 1686 (2007).

  44. 44.

    Argyropoulos, C., Estakhri, N. M., Monticone, F. & Alu, A. Negative refraction, gain and nonlinear effects in hyperbolic metamaterials. Opt. Express 21, 15037–15047 (2013).

  45. 45.

    Hoffman, A. J. et al. Negative refraction in semiconductor metamaterials. Nat. Mater. 6, 946–950 (2007).

  46. 46.

    Shalaev, V. M. et al. Negative index of refraction in optical metamaterials. Opt. Lett. 30, 3356–3358 (2005).

  47. 47.

    Lin, X. et al. All-angle negative refraction of highly squeezed plasmon and phonon polaritons in graphene-boron nitride heterostructures. Proc. Natl Acad. Sci. USA 114, 6717–6721 (2017).

  48. 48.

    Qian, C. et al. Multifrequency superscattering from subwavelength hyperbolic structures. ACS Photonics 5, 1506–1511 (2018).

  49. 49.

    Cortes, C. L., Newman, W., Molesky, S. & Jacob, Z. Quantum nanophotonics using hyperbolic metamaterials. J. Opt. 14, 063001 (2012).

  50. 50.

    Giles, A. J. et al. Imaging of anomalous internal reflections of hyperbolic phonon-polaritons in hexagonal boron nitride. Nano Lett. 16, 3858–3865 (2016).

  51. 51.

    Li, P. et al. Hyperbolic phonon-polaritons in boron nitride for near-field optical imaging and focusing. Nat. Commun. 6, 7507 (2015).

  52. 52.

    Folland, T. G. et al. Probing hyperbolic polaritons using infrared attenuated total reflectance micro-spectroscopy. MRS Commun. 8, 1418–1425 (2018).

  53. 53.

    Dai, S. et al. Internal nanostructure diagnosis with hyperbolic phonon polaritons in hexagonal boron nitride. Nano Lett. 18, 5205–5210 (2018).

  54. 54.

    Brown, L. V. et al. Nanoscale mapping and spectroscopy of nonradiative hyperbolic modes in hexagonal boron nitride nanostructures. Nano Lett. 18, 1628–1636 (2018).

  55. 55.

    Sun, Z., Gutierrez-Rubio, A., Basov, D. N. & Fogler, M. M. Hamiltonian optics of hyperbolic polaritons in nanogranules. Nano Lett. 15, 4455–4460 (2015).

  56. 56.

    Li, P. et al. Reversible optical switching of highly confined phonon-polaritons with an ultrathin phase-change material. Nat. Mater. 15, 870–875 (2016).

  57. 57.

    Folland, T. G. et al. Reconfigurable infrared hyperbolic metasurfaces using phase change materials. Nat. Commun. 9, 4371 (2018).

  58. 58.

    Michel, A.-K. U. et al. Using low-loss phase-change materials for mid-infrared antenna resonance tuning. Nano Lett. 13, 3470–3475 (2013).

  59. 59.

    Dunkelberger, A. D. et al. Active tuning of surface phonon polariton resonances via carrier photoinjection. Nat. Photonics 12, 50–56 (2018).

  60. 60.

    Spann, B. T. et al. Photoinduced tunability of the reststrahlen band in 4H-SiC. Phys. Rev. B 93, 085205 (2016).

  61. 61.

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

  62. 62.

    Li, P. et al. Infrared hyperbolic metasurface based on nanostructured van der Waals materials. Science 359, 892–896 (2018).

  63. 63.

    Wang, T. et al. Phonon-polaritonic bowtie nanoantennas: controlling infrared thermal radiation at the nanoscale. ACS Photonics 4, 1753–1760 (2017).

  64. 64.

    Adato, R. et al. Ultra-sensitive vibrational spectroscopy of protein monolayers with plasmonic nanoantenna arrays. Proc. Natl Acad. Sci. USA 106, 19227–19232 (2009).

  65. 65.

    Ma, W. et al. In-plane anisotropic and ultra-low-loss polaritons in a natural van der Waals crystal. Nature 562, 557–562 (2018).

  66. 66.

    Zheng, Z. et al. Highly confined and tunable hyperbolic phonon polaritons in van der Waals semiconducting transition metal oxides. Adv. Mater. 30, 1705318 (2018).

  67. 67.

    Folland, T. G. & Caldwell, J. D. Precise control of infrared polarization using crystal vibrations. Nature 562, 499–501 (2018).

  68. 68.

    Tran, T. T., Bray, K., Ford, M. J., Toth, M. & Aharonovich, I. Quantum emission from hexagonal boron nitride monolayers. Nat. Nanotechnol. 11, 37–41 (2016).

  69. 69.

    Tran, T. T. et al. Robust multicolor single photon emission from point defects in hexagonal boron nitride. ACS Nano 10, 7331–7338 (2016).

  70. 70.

    Jungwirth, N. R. et al. Temperature dependence of wavelength selectable zero-phonon emission from single defects in hexagonal boron nitride. Nano Lett. 16, 6052–6057 (2016).

  71. 71.

    Exarhos, A. L., Hopper, D. A., Grote, R. R., Alkauskas, A. & Bassett, L. C. Optical signatures of quantum emitters in suspended hexagonal boron nitride. ACS Nano 11, 3328–3336 (2017).

  72. 72.

    Shotan, Z. et al. Photoinduced modification of single-photon emitters in hexagonal boron nitride. ACS Photonics 3, 2490–2496 (2016).

  73. 73.

    Abdi, M., Chou, J.-P., Gali, A. & Plenio, M. B. Color centers in hexagonal boron nitride monolayers: a group theory and ab initio analysis. ACS Photonics 5, 1967–1976 (2018).

  74. 74.

    Tawfik, S. A. et al. First-principles investigation of quantum emission from hBN defects. Nanoscale 9, 13575–13582 (2017).

  75. 75.

    Martínez, L. J. et al. Efficient single photon emission from a high-purity hexagonal boron nitride crystal. Phys. Rev. B 94, 121405 (2016).

  76. 76.

    Tran, T. T. et al. Quantum emission from defects in single-crystalline hexagonal boron nitride. Phys. Rev. Appl. 5, 034005 (2016).

  77. 77.

    Chejanovsky, N. et al. Quantum light in curved low dimensional hexagonal boron nitride systems. Sci. Rep. 7, 14758 (2017).

  78. 78.

    Koperski, M., Nogajewski, K. & Potemski, M. Single photon emitters in boron nitride: more than a supplementary material. Opt. Commun. 411, 158–165 (2018).

  79. 79.

    Hernández-Mínguez, A., Lähnemann, J., Nakhaie, S., Lopes, J. M. J. & Santos, P. V. Luminescent defects in a few-layer h-BN film grown by molecular beam epitaxy. Phys. Rev. Appl. 10, 044031 (2018).

  80. 80.

    Mendelson, N. et al. Bottom up engineering of near-identical quantum emitters in atomically thin materials. Preprint at arXiv https://arxiv.org/abs/1806.01199 (2019).

  81. 81.

    Stern, H. L. et al. Spectrally resolved photodynamics of individual emitters in large-area monolayers of hexagonal boron nitride. ACS Nano 13, 4548–4547 (2019).

  82. 82.

    Choi, S. et al. Engineering and localization of quantum emitters in large hexagonal boron nitride layers. ACS Appl. Mater. Interfaces 8, 29642–29648 (2016).

  83. 83.

    Ngoc My Duong, H. et al. Effects of high-energy electron irradiation on quantum emitters in hexagonal boron nitride. ACS Appl. Mater. Interfaces 10, 24886–24891 (2018).

  84. 84.

    Proscia, N. V. et al. Near-deterministic activation of room-temperature quantum emitters in hexagonal boron nitride. Optica 5, 1128–1134 (2018).

  85. 85.

    Xu, Z.-Q. et al. Single photon emission from plasma treated 2D hexagonal boron nitride. Nanoscale 10, 7957–7965 (2018).

  86. 86.

    Jungwirth, N. R. & Fuchs, G. D. Optical absorption and emission mechanisms of single defects in hexagonal boron nitride. Phys. Rev. Lett. 119, 057401 (2017).

  87. 87.

    Schell, A. W., Tran, T. T., Takashima, H., Takeuchi, S. & Aharonovich, I. Non-linear excitation of quantum emitters in hexagonal boron nitride multiplayers. APL Photonics 1, 091302 (2016).

  88. 88.

    Wang, Q. et al. Photoluminescence upconversion by defects in hexagonal boron nitride. Nano Lett. 18, 6898–6905 (2018).

  89. 89.

    Bourrellier, R. et al. Bright UV single photon emission at point defects in h-BN. Nano Lett. 16, 4317–4321 (2016).

  90. 90.

    Sontheimer, B. et al. Photodynamics of quantum emitters in hexagonal boron nitride revealed by low-temperature spectroscopy. Phys. Rev. B 96, 121202 (2017).

  91. 91.

    Tran, T. T. et al. Resonant excitation of quantum emitters in hexagonal boron nitride. ACS Photonics 5, 295–300 (2018).

  92. 92.

    Dietrich, A. et al. Observation of Fourier transform limited lines in hexagonal boron nitride. Phys. Rev. B 98, 081414 (2018).

  93. 93.

    Konthasinghe, K. et al. Rabi oscillations and resonance fluorescence from a single hexagonal boron nitride quantum emitter. Optica 6, 542–548 (2019).

  94. 94.

    Noh, G. et al. Stark tuning of single-photon emitters in hexagonal boron nitride. Nano Lett. 18, 4710–4715 (2018).

  95. 95.

    Nikolay, N. et al. Very large and reversible Stark-shift tuning of single emitters in layered hexagonal boron nitride. Phys. Rev. Appl. 11, 041001 (2019).

  96. 96.

    Grosso, G. et al. Tunable and high-purity room temperature single-photon emission from atomic defects in hexagonal boron nitride. Nat. Commun. 8, 705 (2017).

  97. 97.

    Xue, Y. et al. Anomalous pressure characteristics of defects in hexagonal boron nitride flakes. ACS Nano 12, 7127–7133 (2018).

  98. 98.

    Tran, T. T. et al. Deterministic coupling of quantum emitters in 2D materials to plasmonic nanocavity arrays. Nano Lett. 17, 2634–2639 (2017).

  99. 99.

    Nguyen, M. et al. Nanoassembly of quantum emitters in hexagonal boron nitride and gold nanospheres. Nanoscale 10, 2267–2274 (2018).

  100. 100.

    Schell, A. W., Takashima, H., Tran, T. T., Aharonovich, I. & Takeuchi, S. Coupling quantum emitters in 2D materials with tapered fibers. ACS Photonics 4, 761–767 (2017).

  101. 101.

    Kim, S. et al. Photonic crystal cavities from hexagonal boron nitride. Nat. Commun. 9, 2623 (2018).

  102. 102.

    Fröch, J. E., Hwang, Y., Kim, S., Aharonovich, I. & Toth, M. Photonic nanostructures from hexagonal boron nitride. Adv. Opt. Mater. 7, 1801344 (2018).

  103. 103.

    Liu, C.-H. et al. Ultrathin van der Waals metalenses. Nano Lett. 18, 6961–6966 (2018).

  104. 104.

    Doherty, M. W. et al. The nitrogen-vacancy colour centre in diamond. Phys. Rep. 528, 1–45 (2013).

  105. 105.

    Toledo, J. R. et al. Electron paramagnetic resonance signature of point defects in neutron-irradiated hexagonal boron nitride. Phys. Rev. B 98, 155203 (2018).

  106. 106.

    Exarhos, A. L., Hopper, D. A., Patel, R. N., Doherty, M. W. & Bassett, L. C. Magnetic-field-dependent quantum emission in hexagonal boron nitride at room temperature. Nat. Commun. 10, 222 (2019).

  107. 107.

    Feng, J. et al. Imaging of optically active defects with nanometer resolution. Nano Lett. 18, 1739–1744 (2018).

  108. 108.

    Comtet, J. et al. Wide-field spectral super-resolution mapping of optically active defects in hexagonal boron nitride. Nano Lett. 19, 2516–2523 (2019).

  109. 109.

    Kianinia, M. et al. All-optical control and super-resolution imaging of quantum emitters in layered materials. Nat. Commun. 9, 874 (2018).

  110. 110.

    Liu, C-h., Zheng, J., Chen, Y., Fryett, T. & Majumdar, A. Van der Waals materials integrated nanophotonic devices [Invited]. Opt. Mater. Express 9, 384–399 (2019).

  111. 111.

    Rivera, N., Rosolen, G., Joannopoulos, J. D., Kaminer, I. & Soljacic, M. Making two-photon processes dominate on-photon processes using mid-IR phonon polaritons. Proc. Natl Acad. Sci. USA 114, 13607–13612 (2017).

  112. 112.

    Watanabe, K. et al. Hexagonal boron nitride as a new ultraviolet luminescent material and its application — fluorescence properties of hBN single-crystal powder. Diam. Relat. Mater. 20, 849–852 (2011).

  113. 113.

    Watanabe, K., Taniguchi, K., Niiyama, T., Miya, K. & Taniguchi, M. Far-ultraviolet plane-emission handheld device based on hexagonal boron nitride. Nat. Photonics 3, 591–594 (2009).

  114. 114.

    Nanishi, Y. Nobel Prize in Physics: the birth of the blue LED. Nat. Photonics 8, 884–886 (2014).

  115. 115.

    Drost, R. J. & Sadler, B. M. Survey of ultraviolet non-line-of-sight communications. Semicond. Sci. Technol. 29, 084006 (2014).

  116. 116.

    Gil, B. Physics of Wurtzite Nitrides and Oxides (Springer, 2014).

  117. 117.

    Vuong, T. Q. P. et al. Phonon symmetries in hexagonal boron nitride probed by incoherent light emission. 2D Mater. 4, 011004 (2017).

  118. 118.

    Xu, Y.-N. & Ching, W. Y. Calculation of ground-state and optical properties of boron nitrides in the hexagonal, cubic, and wurtzite structures. Phys. Rev. B 44, 7787–7798 (1991).

  119. 119.

    Furthmuller, J., Hafner, J. & Kresse, G. Ab initio calculation of the structural and electronic properties of carbon and boron nitride using ultrasoft pseudopotentials. Phys. Rev. B 50, 15606–15622 (1994).

  120. 120.

    Blase, X., Rubio, A., Louie, S. G. & Cohen, M. L. Quasiparticle band structure of bulk hexagonal boron nitride and related systems. Phys. Rev. B 51, 6868–6875 (1995).

  121. 121.

    Arnaud, B., Lebegue, S., Rabiller, P. & Alouani, M. Huge excitonic effects in layered hexagonal boron nitride. Phys. Rev. Lett. 96, 026402 (2006).

  122. 122.

    Gao, S.-P. Crystal structures and band gap characters of hBN polytypes predicted by dispersion corrected DFT and GW method. Solid State Commun. 152, 1817–1820 (2012).

  123. 123.

    Schuster, R., Habenicht, C., Ahmad, M., Knupfer, M. & Buchner, B. Direct observation of the lowest indirect exciton state in the bulk of hexagonal boron nitride. Phys. Rev. B 97, 041201 (2018).

  124. 124.

    Vuong, T. Q. P. et al. Overtones of interlayer shear modes in the phonon-assisted emission spectrum of hexagonal boron nitride. Phys. Rev. B 95, 045207 (2017).

  125. 125.

    Toyozawa, Y. Theory of line-shapes of the exciton absorption bands. Progress Theor. Phys. 20, 53–81 (1958).

  126. 126.

    Vuong, T. Q. P. et al. Exciton-phonon interaction in the strong-coupling regime in hexagonal boron nitride. Phys. Rev. B 95, 211202(R) (2017).

  127. 127.

    Watanabe, K., Taniguchi, K., Kuroda, T. & Tsuda, O. Time-resolved photoluminescence in band-edge region of hexagonal boron nitride single crystals. Diam. Relat. Mater. 17, 830–832 (2008).

  128. 128.

    Cao, X. K., Clubine, B., Edgar, J. H., Lin, J. Y. & Jiang, H. X. Two-dimensional excitons in three-dimensional hexagonal boron nitride. Appl. Phys. Lett. 103, 191106 (2013).

  129. 129.

    Cassabois, G., Valvin, P. & Gil, B. Intervalley scattering in hexagonal boron nitride. Phys. Rev. B 93, 035207 (2016).

  130. 130.

    Chichibu, S. F., Ishikawa, Y., Kominami, H. & Hara, K. Nearly temperature-independent ultraviolet light emission intensity of indirect excitons in hexagonal BN microcrystals. J. Appl. Phys. 123, 065104 (2018).

  131. 131.

    Schue, L. et al. Direct and indirect excitons with high binding energies in hBN. Phys. Rev. Lett. 122, 067401 (2018).

  132. 132.

    Cannuccia, E., Monserrat, B. & Attaccalite, C. Theory of phonon-assisted luminescence in solids: application to hexagonal boron nitride. Phys. Rev. B 99, 081109(R) (2018).

  133. 133.

    Paleari, F., Miranda, H. P. C., Molina-Sanchez, A. & Wirtz, L. Exciton-phonon coupling in the UV absorption and emission spectra of bulk hexagonal boron nitride. Phys. Rev. Lett. 122, 187401 (2018).

  134. 134.

    Paleari, F. et al. Excitons in few-layer hexagonal boron nitride: Davydov splitting and surface localization. 2D Mater. 5, 045017 (2018).

  135. 135.

    Elias, C. et al. Direct band-gap crossover in epitaxial monolayer boron nitride. Nat. Commun. 10, 2639 (2019).

  136. 136.

    Mak, K. F., Lee, C., Hone, J., Shan, J. & Heinz, T. F. Atomically thin MoS2: a new direct-gap semiconductor. Phys. Rev. Lett. 105, 136805 (2010).

  137. 137.

    Al Balushi, Z. Y. et al. Two-dimensional gallium nitride realized via graphene encapsulation. Nat. Mater. 15, 1166–1171 (2016).

  138. 138.

    Schue, L. et al. Dimensionality effects on the luminescence properties of hBN. Nanoscale 8, 6986–6993 (2016).

  139. 139.

    Akamaru, H., Onodera, A., Endo, T. & Mishima, O. Pressure dependence of the optical-absorption edge of AlN and graphite-type BN. J. Phys. Chem. Solids 63, 887–894 (2002).

  140. 140.

    Koskelo, J. et al. Excitons in van der Waals materials: from monolayer to bulk hexagonal boron nitride. Phys. Rev. B 95, 035125 (2017).

  141. 141.

    Vinogradov, V. L. & Kostanovskii, A. V. Determination of the melting parameters of boron-nitride [in Russian]. High Temp. 29, 901–908 (1991).

  142. 142.

    Kubota, Y., Watanabe, K., Tsuda, O. & Taniguchi, K. Deep ultraviolet light-emitting hexagonal boron nitride synthesized at atmospheric pressure. Science 317, 932–934 (2007).

  143. 143.

    Kubota, Y., Watanabe, K., Tsuda, O. & Taniguchi, K. Hexagonal boron nitride single crystal growth at atmospheric pressure using Ni-Cr solvent. Chem. Mater. 20, 1661–1663 (2008).

  144. 144.

    Liu, S. et al. Large scale growth of high quality hexagonal boron nitride crystals at atmospheric pressure from an iron-chromium flux. Cryst. Growth Des. 17, 4932–4935 (2017).

  145. 145.

    Liu, S. et al. Single crystal growth of millimeter-sized monoisotopic hexagonal boron nitride. Chem. Mater. 30, 6222–6225 (2018).

  146. 146.

    Yuan, C. et al. Modulating the thermal conductivity in hexagonal boron nitride via controlled boron isotope concentration. Commun. Phys. 2, 43 (2019).

  147. 147.

    Cusco, R. et al. Isotopic effects on phonon anharmonicity in layered van der Waals crystals: isotopically pure hexagonal boron nitride. Phys. Rev. B 97, 155435 (2018).

  148. 148.

    Maity, A., Grenadier, S. L., Li, J., Lin, J. Y. & Jiang, H. X. Hexagonal boron nitride neutron detectors with high detection efficiencies. J. Appl. Phys. 123, 044501 (2018).

  149. 149.

    Sun, J. et al. Recent progress in the tailored growth of two-dimensional hexagonal boron nitride via chemical vapour deposition. Chem. Soc. Rev. 47, 4242–4257 (2018).

  150. 150.

    Wang, H.-Z., Zhao, Y., Xie, Y., Ma, X. & Zhang, X. Recent progress in synthesis of two-dimensional hexagonal boron nitride. J. Semicond. 38, 031003 (2017).

  151. 151.

    Laleyan, D. A. et al. Effect of growth temperature on the structural and optical properties of few-layer hexagonal boron nitride by molecular beam epitaxy. Opt. Express 26, 23031–23039 (2018).

  152. 152.

    Chubarov, M. et al. Epitaxial CVD growth of sp2-hybridized boron nitride using aluminum nitride as buffer layer. Phys. Status Solidi Rapid Res. Lett. 5, 397–399 (2011).

  153. 153.

    Henry, A., Chubarov, M., Czigany, Z., Garbrecht, M. & Hogberg, H. Early stages of growth and crystal structure evolution of boron nitride thin films. Jpn. J. Appl. Phys. 55, 05FD06 (2016).

  154. 154.

    Dahal, R. et al. Epitaxially grown semiconducting hexagonal boron nitride as a deep ultraviolet photonic material. Appl. Phys. Lett. 98, 211110 (2011).

  155. 155.

    Lee, J. S. et al. Wafer-scale single-crystal hexagonal boron nitride film via self-collimated grain formation. Science 362, 817–821 (2018).

  156. 156.

    Tan, L. et al. Self-aligned single-crystalline hexagonal boron nitride arrays: toward higher integrated electronic devices. Adv. Electron. Mater. 1, 1500223 (2015).

  157. 157.

    Kobayashi, Y., Kumakura, K., Akasaka, T. & Makimoto, T. Layered boron nitride as a release layer for mechanical transfer of GaN-based devices. Nature 484, 223–227 (2012).

  158. 158.

    Makimoto, T., Kumakura, K., Kobayashi, Y., Akasaka, T. & Yamamoto, H. A vertical InGaN/GaN light-emitting diode fabricated on a flexible substrate by a mechanical transfer method using BN. Appl. Phys. Express 5, 072102 (2012).

  159. 159.

    Ayari, T. et al. Heterogeneous integration of thin-film InGaN-based solar cells on foreign substrates with enhanced performance. ACS Photonics 5, 3003–3008 (2018).

  160. 160.

    Hu, S. et al. Proton transport through one-atom-thick crystals. Nature 516, 227–230 (2014).

  161. 161.

    Schue, L., Stenger, I., Fossard, F., Loiseau, A. & Barjon, J. Characterization methods dedicated to nanometer-thick hBN layers. 2D Mater. 4, 015028 (2017).

  162. 162.

    Wang, L. et al. One-dimensional electrical contact to a two-dimensional material. Science 342, 614–617 (2013).

  163. 163.

    Castellanos-Gomez, A. Why all the fuss about 2D semiconductors? Nat. Photonics 10, 202–204 (2016).

  164. 164.

    Taychatanapat, T., Watanabe, K., Taniguchi, T. & Jarillo-Herrero, P. Electrically tunable transverse magnetic focusing in graphene. Nat. Phys. 9, 225–229 (2013).

  165. 165.

    Yankowitz, M., Xue, J. & LeRoy, B. J. Graphene on hexagonal boron nitride. J. Phys. Condens. Matter 26, 303201 (2014).

  166. 166.

    Yankowitz, M., Ma, Q., Jarillo-Herrero, P. & LeRoy, B. J. van der Waals heterostructures combining graphene and hexagonal boron nitride. Nat. Rev. Phys. 1, 112–125 (2019).

  167. 167.

    Decker, R. et al. Local electronic properties of graphene on a BN substrate via scanning tunneling microscopy. Nano Lett. 11, 2291–2295 (2011).

  168. 168.

    Xue, J. M. et al. Scanning tunneling microscopy and spectroscopy of ultra-flat graphene on hexagonal boron nitride. Nat. Mater. 10, 282–285 (2011).

  169. 169.

    Yankowitz, M. et al. Emergence of superlattice Dirac points in graphene on hexagonal boron nitride. Nat. Phys. 8, 382–386 (2012).

  170. 170.

    Tang, S. et al. Precisely aligned graphene grown on hexagonal boron nitride by catalyst free chemical vapor deposition. Sci. Rep. 3, 2666 (2013).

  171. 171.

    Li, G., Luican, A. & Andrei, E. Y. Scanning tunneling spectroscopy of graphene on graphite. Phys. Rev. Lett. 102, 176804 (2009).

  172. 172.

    Shi, Z. et al. Gate-dependent pseudospin mixing in graphene/boron nitride moiré superlattices. Nat. Photonics 10, 743–747 (2014).

  173. 173.

    Tomadin, A., Guinea, F. & Polini, M. Generation and morphing of plasmons in graphene superlattices. Phys. Rev. B 90, 161406(R) (2014).

  174. 174.

    Xian, L., Kennes, D. M., Tancogne-Dejean, N., Altarelli, M. & Rubio, A. Multi-flat bands and strong correlations in twisted bilayer boron nitride. Preprint at arXiv https://arxiv.org/abs/1812.08097 (2018).

  175. 175.

    Cao, Y. et al. Unconventional superconductivity in magic-angle graphene superlattices. Nature 556, 43–50 (2018).

  176. 176.

    Schmidt, H. et al. Tunable graphene system with two decoupled monolayers. Appl. Phys. Lett. 93, 172108 (2008).

  177. 177.

    Sanchez-Yamagishi, J. et al. Quantum Hall effect, screening, and layer-polarized insulating states in twisted bilayer graphene. Phys. Rev. Lett. 108, 076601 (2012).

  178. 178.

    Luican, A. et al. Observation of Van Hove singularities in twisted graphene layers. Nat. Phys. 6, 109–113 (2010).

  179. 179.

    Lee, D. S. et al. Quantum Hall effect in twisted bilayer graphene. Phys. Rev. Lett. 107, 216602 (2011).

  180. 180.

    Sanchez-Yamagishi, J. et al. Helical edge states and fractional quantum Hall effect in a graphene electron-hole bilayer. Nat. Nanotechnol. 12, 118–122 (2017).

  181. 181.

    Liu, K. et al. Evolution of interlayer coupling in twisted molybdenum disulfide bilayers. Nat. Commun. 5, 4966 (2014).

  182. 182.

    Barbier, M., Vasilopoulos, P. & Peeters, F. M. Extra Dirac points in the energy spectrum for superlattices on single-layer graphene. Phys. Rev. B 81, 075438 (2010).

  183. 183.

    Woods, C. R. et al. Commensurate–incommensurate transition in graphene on hexagonal boron nitride. Nat. Phys. 10, 451–456 (2014).

  184. 184.

    Hunt, B. et al. Massive Dirac fermions and Hofstadter butterfly in a van der Waals heterostructure. Science 340, 1427–1430 (2013).

  185. 185.

    Yeh, P.-C. et al. Direct measurement of the tunable electronic structure of bilayer MoS2 by interlayer twist. Nano Lett. 16, 953–959 (2016).

  186. 186.

    Chari, T., Ribeiro-Palau, R., Dean, C. R. & Shepard, K. Resistivity of rotated graphite-graphene contacts. Nano Lett. 16, 4477–4482 (2016).

  187. 187.

    Ribeiro-Palau, R. et al. Twistable electronics with dynamically rotatable heterostructures. Science 361, 690–693 (2018).

  188. 188.

    Senellart, P., Solomon, G. & White, A. High-performance semiconductor quantum-dot single-photon sources. Nat. Nanotechnol. 12, 1026–1039 (2017).

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Acknowledgements

J.D.C. acknowledges the support of Vanderbilt University for its financial support of his effort in this work. Additionally, J.D.C. and D.N.B. offer their sincere thanks to Misha Fogler for his code, used to calculate the hyperbolic dispersion of hBN in Fig. 2. J.D.C. expresses his thanks to Joseph Matson for his efforts in improving the hyperbolic polariton image in Fig. 1 and for Fig. 2b. J.H.E. appreciates support for crystal growth from the National Science Foundation, award number CMMI 1538127. This work was financially supported by the network GaNeX (ANR-11-LABX-0014). GaNeX belongs to the publicly funded ‘Investissements d’Avenir’ programme managed by the French ANR agency. I.A. gratefully acknowledges financial support from the Australian Research Council (via DP180100077), the Asian Office of Aerospace Research and Development grant FA2386-17-1-4064 and the Office of Naval Research Global under grant number N62909-18-1-2025. The work at Columbia University on van der Waals materials and heterostructures is supported as part of Programmable Quantum Materials, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under award DE-SC0019443. Research on photonic circuits is supported by AFOSR: FA9550-15-1-0478. Research on hybrid polaritonic structures is supported by ONR-N000014-18-1-2722. Development of nano-optics instrumentation at Columbia is supported by DOE-BES DE-SC0018218. D.N.B. is a Gordon and Betty Moore Foundation investigator under EPiQS Initiative Grant GBMF4533.

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Correspondence to Joshua D. Caldwell.

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