Research Repository

See what's under the surface


Tunnel spectroscopy of localised electronic states in hexagonal boron nitride (2018)
Journal Article
Greenaway, M., Vdovin, E., Ghazaryan, D., Misra, A., Mischenko, A., Cao, Y., …Eaves, L. (2018). Tunnel spectroscopy of localised electronic states in hexagonal boron nitride. Communications Physics, 1, doi:10.1038/s42005-018-0097-1

Hexagonal boron nitride is a large band gap layered crystal, frequently incorporated in van der Waals heterostructures as an insulating or tunnel barrier. Localised states with energies within its band gap can emit visible light, relevant to applicat... Read More

Photo-quantum Hall effect and light-induced charge transfer at the interface of graphene/InSe heterostructures (2018)
Journal Article
Bhuiyan, M. A., Kudrynskyi, Z. R., Mazumder, D., Greener, J. D., Makarovsky, O., Mellor, C. J., …Patanè, A. (2019). Photo-quantum Hall effect and light-induced charge transfer at the interface of graphene/InSe heterostructures. Advanced Functional Materials, 29(3), doi:10.1002/adfm.201805491

The transfer of electronic charge across the interface of two van der Waals crystals can underpin the operation of a new class of functional devices. Amongst van der Waals semiconductors, an exciting and rapidly growing development involves the “post... Read More

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), doi:10.3390/ma11071119. ISSN 1996-1944

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

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, doi:10.1021/acs.nanolett.8b01223. ISSN 1530-6984

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

Magnon-assisted tunnelling in van der Waals heterostructures based on CrBr3 (2018)
Journal Article
Ghazaryan, D., Greenaway, M., Wang, Z., Guarochico-Moreira, V., Vera-Marun, I., Yin, J., …Misra, A. (2018). Magnon-assisted tunnelling in van der Waals heterostructures based on CrBr3. doi:10.1038/s41928-018-0087-z. ISSN 2520-1131

Van der Waals heterostructures, which are composed of layered two-dimensional materials, offer a platform to investigate a diverse range of physical phenomena and could be of use in a variety of applications. Heterostructures containing two-dimension... Read More

High-order fractal states in graphene superlattices (2018)
Journal Article
Krishna Kumar, R., Mishchenko, A., Chen, X., Pezzini, S., Auton, G., Ponomarenko, L., …Geim, A. (2018). High-order fractal states in graphene superlattices. Proceedings of the National Academy of Sciences, 115(20), doi:10.1073/pnas.1804572115. ISSN 1091-6490

Graphene superlattices were shown to exhibit high-temperature quantum oscillations due to periodic emergence of delocalized Bloch states in high magnetic fields such that unit fractions of the flux quantum pierce a superlattice unit cell. Under these... Read More

Epitaxial growth of γ-InSe and α, β, and γ-In2Se3 on ε-GaSe (2018)
Journal Article
Balakrishnan, N., Steer, E. D., Smith, E. F., Kudrynskyi, Z. R., Kovalyuk, Z. D., Eaves, L., …Beton, P. H. (2018). Epitaxial growth of γ-InSe and α, β, and γ-In2Se3 on ε-GaSe. 2D Materials, 5(3), doi:10.1088/2053-1583/aac479. ISSN 2053-1583

We demonstrate that γ-InSe and the α, β and γ phases of In2Se3 can be grown epitaxially on ε-GaSe substrates using a physical vapour transport method. By exploiting the temperature gradient within the tube furnace, we can grow selectively different p... Read More

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), doi:10.1116/1.5011280. ISSN 2166-2746

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

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), doi:10.1021/acs.nanolett.7b04453. ISSN 1530-6984

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

A giant quantum Hall plateau in graphene coupled to an InSe van der Waals crystal (2017)
Journal Article
Kudrynskyi, Z. R., Bhuiyan, M. A., Makarovsky, O., Greener, J. D., Vdovin, E. E., Kovalyuk, Z. D., …Patanè, A. (2017). A giant quantum Hall plateau in graphene coupled to an InSe van der Waals crystal. Physical Review Letters, 119(15), doi:10.1103/PhysRevLett.119.157701. ISSN 0031-9007

We report on a “giant” quantum Hall effect plateau in a graphene-based field effect transistor where graphene is capped by a layer of the van der Waals crystal InSe. The “giant” quantum Hall effect plateau arises from the close alignment of the condu... Read More

An atomic carbon source for high temperature molecular beam epitaxy of graphene (2017)
Journal Article
Albar, J., Summerfield, A., Cheng, T. S., Davies, A., Smith, E., Khlobystov, A. N., …Novikov, S. V. (in press). An atomic carbon source for high temperature molecular beam epitaxy of graphene. Scientific Reports, 7(1), doi:10.1038/s41598-017-07021-1. ISSN 2045-2322

We report the use of a novel atomic carbon source for the molecular beam epitaxy (MBE) of graphene layers on hBN flakes and on sapphire wafers at substrate growth temperatures of ~1400 °C. The source produces a flux of predominantly atomic carbon, wh... Read More

High-temperature quantum oscillations caused by recurring Bloch states in graphene superlattices (2017)
Journal Article
Krishna Kumar, R., Chen, X., Auton, G., Mishchenko, A., Bandurin, D. A., Morozov, S., …Geim, A. (2017). High-temperature quantum oscillations caused by recurring Bloch states in graphene superlattices. Science, 357(6347), doi:10.1126/science.aal3357. ISSN 0036-8075

Cyclotron motion of charge carriers in metals and semiconductors leads to Landau quantization and magneto-oscillatory behavior in their properties. Cryogenic temperatures are usually required to observe these oscillations. We show that graphene super... Read More

Enhancing optoelectronic properties of SiC-grown graphene by a surface layer of colloidal quantum dots (2017)
Journal Article
Makarovsky, O., Turyanska, L., Mori, N., Greenaway, M., Eaves, L., Patanè, A., …Yakimova, R. (in press). Enhancing optoelectronic properties of SiC-grown graphene by a surface layer of colloidal quantum dots. 2D Materials, 4(3), doi:10.1088/2053-1583/aa76bb. ISSN 2053-1583

We report a simultaneous increase of carrier concentration, mobility and photoresponsivity when SiC-grown graphene is decorated with a surface layer of colloidal PbS quantum dots, which act as electron donors. The charge on the ionised dots is spatia... Read More

Fast, multicolor photodetection with graphene-contacted p-GaSe/n-InSe van der Waals heterostructures (2017)
Journal Article
Yan, F., Zhao, L., Patanè, A., Hu, P., Wei, X., Luo, W., …Wang, K. (in press). Fast, multicolor photodetection with graphene-contacted p-GaSe/n-InSe van der Waals heterostructures. Nanotechnology, doi:10.1088/1361-6528/aa749e. ISSN 0957-4484

The integration of different two-dimensional materials within a multilayer van der Waals (vdW) heterostructure offers a promising technology for high performance opto-electronic devices such as photodetectors and light sources. Here we report on the... Read More

Engineering p-n junctions and bandgap tuning of InSe nanolayers by controlled oxidation (2017)
Journal Article
Balakrishnan, N., Kudrynskyi, Z. R., Smith, E. F., Fay, M. W., Makarovsky, O., Kovalyuk, Z. D., …Patanè, A. (2017). Engineering p-n junctions and bandgap tuning of InSe nanolayers by controlled oxidation. 2D Materials, 4(2), doi:10.1088/2053-1583/aa61e0. ISSN 2053-1583

Exploitation of two-dimensional (2D) van der Waals (vdW) crystals can be hindered by the deterioration of the crystal surface over time due to oxidation. On the other hand, the existence of a stable oxide at room temperature can offer prospects for s... Read More

Mobility enhancement of CVD graphene by spatially correlated charges (2017)
Journal Article
Turyanska, L., Makarovsky, O., Eaves, L., Patanè, A., & Mori, N. (2017). Mobility enhancement of CVD graphene by spatially correlated charges. 2D Materials, 4(2), doi:10.1088/2053-1583/aa55b4. ISSN 2053-1583

The manuscript presents a strategy for enhancing the carrier mobility of single layer CVD graphene (CVD SLG) based on spatially correlated charges. Our Monte Carlo simulations, numerical modeling and the experimental results confirm that spatial corr... Read More

High electron mobility, quantum Hall effect and anomalous optical response in atomically thin InSe (2016)
Journal Article
Bandurin, D. A., Tyurnina, A. V., Yu, G. L., Mishchenko, A., Zólyomi, V., Morozov, S. V., …Cao, Y. (in press). High electron mobility, quantum Hall effect and anomalous optical response in atomically thin InSe. Nature Nanotechnology, doi:10.1038/nnano.2016.242. ISSN 1748-3387

A decade of intense research on two-dimensional (2D) atomic crystals has revealed that their properties can differ greatly from those of the parent compound. These differences are governed by changes in the band structure due to quantum confinement a... Read More

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. (in press). Hexagonal boron nitride tunnel barriers grown on graphite by high temperature molecular beam epitaxy. Scientific Reports, 6, doi:10.1038/srep34474. ISSN 2045-2322

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