Nanomaterials growth
Nano-manufacturing the materials of tomorrow
Semiconducting Nanowires
We explore catalytic growth, self-catalysed growth and selective area epitaxy. Large local supersaturations open many new kinetic pathways, which leads to striking new crystal growth behaviour on the nanoscale and makes this an extremely exciting field of study. We study phase behaviour of nano-scale alloys, the atomistic dynamics of nano-crystal nucleation and dynamics at liquid-solid, solid-gas and solid-solid interfaces in realistic process environments. Such fundamental understanding then allows us to devise new approaches to crystal growth and to engineer novel functional heterostructures for advanced electronic, photonic and quantum devices.
In collaboration with:
Dr F. Ross (IBM)
References:
Jacobsson et al. Nature 531, 317 (2016)
Panciera et al. Nature Materials 14, 820 (2015)
Hofmann et al. Nature Mat. 7, 372 (2008)2D materials
Layered materials, such as graphite, h-BN or transition metal dichalcogenides (TMDs) show a characteristic strong, predominantly covalent intra-layer bonding contrasted by weak inter-layer coupling dominated by van der Waals forces. Changes to these inter-layer interactions and stacking sequence lead to dramatic differences in the electronic structure, hence lead to distinct properties for 2D mono-layer or few layers compared to the bulk material. The idea of engineering mono- and few-layer stacking can be generalised into the concept of van der Waals heterostructures, i.e. the layer-by-layer engineering at atomic level of completely new designer materials that are non-existent in nature and that allow the tailoring of superior or hitherto unknown properties, phenomena and device concepts. We investigate the direct chemical vapour deposition (CVD) of highly-crystalline, low defect density “electronic-grade” mono- or few-layer films of 2D materials continuous over large areas or at specific locations on different application-relevant substrates. We seek a systematic understanding of the fundamental growth mechanisms of 2D crystals as basis for scalable integrated manufacturing pathways.
In collaboration with:
Aixtron (UK)
References:
Weatherup et al. Nano Lett. 16, 6196 (2016)
Caneva et al. Nano Lett. 16, 1250 (2016)
Hofmann et al J.Phys. Chem. Lett. 6, 2714 (2015)Carbon nanotubes
The unique electronic, thermal, and mechanical properties of carbon nanotubes (CNTs) closely relate to the tubular atomistic structure. To unlock the full application potential of CNTs, not only scalability but also structural selectivity is required for their growth. We investigate the fundamental mechanisms how CNTs nucleate and how their structure and chirality can be controlled. This links to heterogeneous catalysis and industrial reactor design.
In collaboration with:
Prof. J. Robertson
References:
Wirth et al. Chem. Mater. 24, 4633 (2012)
Hofmann et al. Nano Lett. 7, 602 (2007)