Hexagonal Boron Nitride (hBN) has emerged as a very versatile wide band-gap semiconductor material which has attracted considerable attention in recent years primarily as an optoelectronic material suitable for developing UV LED (1-3). In addition to this, owing to its unique 2D layered crystal structure with atomically smooth surface and wide band-gap, hBN, has also proven to be one of the most suitable substrate and dielectric layer for graphene and other 2D materials based electronic and optoelectronic devices, including epitaxial growth of graphene (4-6). In a different but related application, hBN has also been utilized as a release layer for conventional III-Nitride LED hetero-structures grown on sapphire substrates. Herein, individual layers of hBN, held together by weak van der Waal forces (as opposed to strong covalent bonds) form a shear plane and facilitate convenient detachment device structures from substrates post epitaxy (7, 8). This furthermore opens new avenues such as, easy transfer onto flexible substrates and adequate mitigation of deleterious effects, most common of which is cracking of epilayers due to tensile and compressive stress (9). In a recent and emerging application, formation of NV (Nitrogen-Vacancy) centres in hBN crystals has been demonstrated which are found to be robust and active at room temperature (10, 11). Just like its diamond counterpart, application of NV centres (in hBN) as single photon sources has been envisioned in field of quantum computing and bio-imaging and bio-labelling.

In order to realize many of the applications described above, we are exploring the growth of hBN using metal organic chemical vapour deposition (MOCVD) techniques on sapphire and silicon substrates. One of the primary goals of my research study is to develop and optimize the MOCVD process for growing high quality hBN epilayers with low defect density. The grown material is characterized using a wide range of techniques allowing a comprehensive study of effect of individual growth parameters on material quality. In this seminar, I will provide a brief overview of various applications of hBN and present some of our recent results on the growth and characterization study of hBN.

References

1. Watanabe K, Taniguchi T, Kanda H. Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal. Nature Materials. 2004;3(6):404-9.
2. Watanabe K, Taniguchi T, Niiyama T, Miya K, Taniguchi M. Far-ultraviolet plane-emission handheld device based on hexagonal boron nitride. Nat Photonics. 2009;3(10):591-4.
3. Majety S, Li J, Cao XK, Dahal R, Pantha BN, Lin JY, et al. Epitaxial growth and demonstration of hexagonal BN/AlGaN p-n junctions for deep ultraviolet photonics. Appl Phys Lett. 2012;100(6):061121.
4. Dean CR, Young AF, Meric I, Lee C, Wang L, Sorgenfrei S, et al. Boron nitride substrates for high-quality graphene electronics. Nat Nanotechnol. 2010;5(10):722-
5. Dean C, Young AF, Wang L, Meric I, Lee GH, Watanabe K, et al. Graphene based heterostructures. Solid State Commun. 2012;152(15):1275-82.
6. Geim AK, Grigorieva IV. Van der Waals heterostructures. Nature. 2013;499(7459):419-25.
7. Kobayashi Y, Kumakura K, Akasaka T, Makimoto T. Layered boron nitride as a release layer for mechanical transfer of GaN-based devices. Nature. 2012;484(7393):223-7.
8. Ayari T, Sundaram S, Li X, Gmili YE, Voss PL, Salvestrini JP, et al. Wafer-scale controlled exfoliation of metal organic vapor phase epitaxy grown InGaN/GaN multi quantum well structures using low-tack two-dimensional layered h-BN. Appl Phys Lett. 2016;108(17):171106.
9. Zhu D, Wallis DJ, Humphreys CJ. Prospects of III-nitride optoelectronics grown on Si. Rep Prog Phys. 2013;76(10).
10. Tran TT, Elbadawi C, Totonjian D, Lobo CJ, Grosso G, Moon H, et al. Robust Multicolor Single Photon Emission from Point Defects in Hexagonal Boron Nitride. Acs Nano. 2016;10(8):7331-8.
11. Tran TT, Bray K, Ford MJ, Toth M, Aharonovich I. Quantum emission from hexagonal boron nitride monolayers. Nat Nano. 2016;11(1):37-41.