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Direct band-gap crossover in epitaxial monolayer boron nitride (2019)
Journal Article
Elias, C., Valvin, P., Pelini, T., Summerfield, A., Mellor, C., Cheng, T., …Cassabois, G. (2019). Direct band-gap crossover in epitaxial monolayer boron nitride. Nature Communications, 10, Article 2639. https://doi.org/10.1038/s41467-019-10610-5

Hexagonal boron nitride is a large band-gap insulating material which complements the electronic and optical properties of graphene and the transition metal dichalcogenides. However, the intrinsic optical properties of monolayer boron nitride remain... Read More about Direct band-gap crossover in epitaxial monolayer boron nitride.

Composition and strain relaxation of In x Ga1−x N graded core–shell nanorods (2018)
Journal Article
Soundararajah, Q. Y., Webster, R. F., Griffiths, I. J., Novikov, S. V., Foxon, C. T., & Cherns, D. (2018). Composition and strain relaxation of In x Ga1−x N graded core–shell nanorods. Nanotechnology, 29(40), Article 405706. https://doi.org/10.1088/1361-6528/aad38d

Two In x Ga1−x N nanorod samples with graded In compositions of x = 0.5–0 (Ga-rich) and x = 0.5–1 (In-rich) grown by molecular beam epitaxy were studied using transmission electron microscopy. The nanorods had a wurtzite crystal structure with growth... Read More about Composition and strain relaxation of In x Ga1−x N graded core–shell nanorods.

High-temperature molecular beam epitaxy of hexagonal boron nitride with high active nitrogen fluxes (2018)
Journal Article
Cheng, T. S., Summerfield, A., Mellor, C. J., Khlobystov, A. N., Eaves, L., Foxon, C. T., …Novikov, S. V. (2018). High-temperature molecular beam epitaxy of hexagonal boron nitride with high active nitrogen fluxes. Materials, 11(7), https://doi.org/10.3390/ma11071119

Hexagonal boron nitride (hBN) has attracted much attention as a key component in van der Waals heterostructures and as a wide band gap material for deep-ultraviolet devices. We have recently demonstrated plasma-assisted molecular beam epitaxy (PA-MBE... Read More about High-temperature molecular beam epitaxy of hexagonal boron nitride with high active nitrogen fluxes.

Moiré-modulated conductance of hexagonal boron nitride tunnel barriers (2018)
Journal Article
Summerfield, A., Kozikov, A., Cheng, T. S., Davies, A., Cho, Y., Khlobystov, A. N., …Beton, P. H. (in press). Moiré-modulated conductance of hexagonal boron nitride tunnel barriers. Nano Letters, https://doi.org/10.1021/acs.nanolett.8b01223

Monolayer hexagonal boron nitride (hBN) tunnel barriers investigated using conductive atomic force microscopy reveal moiré patterns in the spatial maps of their tunnel conductance consistent with the formation of a moiré superlattice between the hB... Read More about Moiré-modulated conductance of hexagonal boron nitride tunnel barriers.

High-temperature molecular beam epitaxy of hexagonal boron nitride layers (2018)
Journal Article
Cheng, T. S., Summerfield, A., Mellor, C. J., Davies, A., Khlobystov, A. N., Eaves, L., …Novikov, S. V. (in press). High-temperature molecular beam epitaxy of hexagonal boron nitride layers. Journal of Vacuum Science and Technology B, 36(2), Article 02D103-1. https://doi.org/10.1116/1.5011280

The growth and properties of hexagonal boron nitride (hBN) have recently attracted much attention due to applications in graphene-based monolayer thick 2D-structures and at the same time as a wide band gap material for deep-ultraviolet device (DUV) a... Read More about High-temperature molecular beam epitaxy of hexagonal boron nitride layers.

Lattice-Matched Epitaxial Graphene Grown on Boron Nitride (2017)
Journal Article
Davies, A., Albar, J., Summerfield, A., Thomas, J. C., Cheng, T. S., Korolkov, V. V., …Beton, P. H. (2018). Lattice-Matched Epitaxial Graphene Grown on Boron Nitride. Nano Letters, 18(1), 498-504. https://doi.org/10.1021/acs.nanolett.7b04453

Lattice-matched graphene on hexagonal boron nitride is expected to lead to the formation of a band-gap but requires the formation of highly strained material and has not hitherto been realised. We demonstrate that aligned, lattice-matched graphene ca... Read More about Lattice-Matched Epitaxial Graphene Grown on Boron Nitride.

Terahertz conductivity of the highly mismatched amorphous alloy, GaNBi (2017)
Journal Article
Vaisakh, C., Foxon, C., Novikov, S. V., & Kini, R. (2017). Terahertz conductivity of the highly mismatched amorphous alloy, GaNBi. Semiconductor Science and Technology, 32(12), Article 125009. https://doi.org/10.1088/1361-6641/aa9288

We report terahertz optical conductivity measurements of the highly mismatched alloy, GaNBi. We find that in these amorphous GaNBi epilayers grown using plasma assisted molecular beam epitaxy, the optical conductivity is enhanced in the samples grown... Read More about Terahertz conductivity of the highly mismatched amorphous alloy, GaNBi.

Intermixing studies in GaN_1−xSb_x highly mismatched alloys (2016)
Journal Article
Sarney, W. L., Svensson, S. P., Ting, M., Segercrantz, N., Walukiewicz, W., Yu, K. M., …Foxon, C. T. (2017). Intermixing studies in GaN_1−xSb_x highly mismatched alloys. Applied Optics, 56(3), B64-B69. https://doi.org/10.1364/AO.56.000B64

GaN1−xSbx with x~ 5-7% is a highly mismatched alloy predicted to have favorable properties for application as an electrode in a photo-electrochemical cell for solar water splitting. In this study, we grew GaN1−xSbx under conditions intended to induce... Read More about Intermixing studies in GaN_1−xSb_x highly mismatched alloys.

Hexagonal Boron Nitride Tunnel Barriers Grown on Graphite by High Temperature Molecular Beam Epitaxy (2016)
Journal Article
Cho, Y., Summerfield, A., Davies, A., Cheng, T. S., Smith, E. F., Mellor, C. J., …Novikov, S. V. (2016). Hexagonal Boron Nitride Tunnel Barriers Grown on Graphite by High Temperature Molecular Beam Epitaxy. Scientific Reports, 6(1), Article 34474. https://doi.org/10.1038/srep34474

We demonstrate direct epitaxial growth of high-quality hexagonal boron nitride (hBN) layers on graphite using high-temperature plasma-assisted molecular beam epitaxy. Atomic force microscopy reveals mono- and few-layer island growth, while conducting... Read More about Hexagonal Boron Nitride Tunnel Barriers Grown on Graphite by High Temperature Molecular Beam Epitaxy.

Characterization of p-GaN1?xAsx/n-GaN PN junction diodes (2016)
Journal Article
Qian, H., Lee, K., Vajargah, S., Novikov, S., Guiney, I., Zhang, S., …Houston, P. (2016). Characterization of p-GaN1−xAsx/n-GaN PN junction diodes. Semiconductor Science and Technology, 31(6), https://doi.org/10.1088/0268-1242/31/6/065020

The structural properties and electrical conduction mechanisms of p-type amorphous GaN1−xAsx/n-type crystalline GaN PN junction diodes are presented. A hole concentration of 8.5×1019 cm−3 is achieved which allows a specific contact resistance of 1.3×... Read More about Characterization of p-GaN1?xAsx/n-GaN PN junction diodes.

Electronic band structure of highly mismatched GaN1?xSbx alloys in a broad composition range (2015)
Journal Article
Segercrantz, N., Yu, K., Ting, M., Sarney, W., Svensson, S., Novikov, S., …Walukiewicz, W. (in press). Electronic band structure of highly mismatched GaN1−xSbx alloys in a broad composition range. Applied Physics Letters, 107(14), Article 142104. https://doi.org/10.1063/1.4932592

In this letter, we study the optical properties of GaN1?xSbx thin films. Films with an Sb fraction up to 42% were synthesized by alternating GaN-GaSb layers at a constant temperature of 325 ?C. The measured optical absorption data of the films are in... Read More about Electronic band structure of highly mismatched GaN1?xSbx alloys in a broad composition range.