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CarbOnlineHagen 2020 - 2D materials talks online

The Carbonhagen conference series (2010-2019) was temporarily revived as "CarbOnlineHagen" to support the research community and open exchange of ideas and results in spring 2020, within the field of 2D materials - science and technology. 

The format was simple. A 40 minute talk is given by a high-level speaker. Moderators will try to answer questions during the talk, and there will be 20 minutes of open discussion with the speaker after that.  

Registration was free, but required to get a link. 

The meeting was organised by the DNRF Centre for Nanostructured Graphene and the NANOMADE section at the Physics department at the Technical University of Denmark. Contact the organisers: Peter Bøggild and Antti-Pekka Jauho at ( 

A follow-up meeting may be organised if there is sufficient interest. 

Cedric Huyghebaert

Sarah Haigh

Mark Hersam

April 17 at 15.00 (CET): Cedric Huyghebaert

First steps of 2D material integration in 300 mm silicon production line
IMEC KU Leuven. Leuven Heverlee, Flanders, Belgium

The development of silicon semiconductor technology has produced breakthroughs in electronics—from the microprocessor in the late 1960s to early 1970s, to automation, computers, and smartphones—by downscaling the physical size of devices and wires to the nanometre regime. Now, graphene and related two-dimensional (2D) materials offer prospects of unprecedented advances in device performance at the atomic limit, and a synergistic combination of 2D materials with silicon chips promises a heterogeneous platform to deliver massively enhanced potential based on silicon technology. Nevertheless, large area co-integration with Si platforms is challenging and progressing at a slow pace suffering from limited reproducibility and a gap between results achieved on encapsulated flakes and synthetic materials. 

It is generally accepted that this is mainly due to a lack of the required infrastructure which allows controlling the interfaces of the 2D materials at large scale. 
In this presentation, we will discuss the processing challenges that we need to research to mature the integration and access the semiconductor standards. Different wafer-level 2D-material growth methods are discussed and benchmarked. A fully automated transfer method will be discussed and remaining challenges are addressed. Finally, we established an integration module for 2D materials in the 300 mm line. We demonstrate the integration of graphene and MX2-based transistors using standard state of the art production tools.

We will demonstrate integrated devices where 2D material was directly deposited or growth on a template surface and transferred to the pre-processed target wafer. The major integration challenges are the limited adhesion and the fragility of the (few)monolayer 2D material. We end up with an outlook of the remaining challenges to make 2D materials integration complete part of the Si processing portfolio  in order to have 2D materials popping up in products that are put on the market in the field of microprocessors, memories, telecommunication, internet of things, sensor, healthcare and bio-applications.

Cedric Huyghebaert is currently program manager of exploratory processes and modules at Imec, dealing with material exploration and early module integration for functional applications. He is the primary investigator for Imec in the Graphene Flagship and deputy of the wafer-scale integration work package. He started as a junior researcher in the materials and component analysis group at Imec. He studied the oxygen beam interactions during sputtering profiling of semiconductors. He received his PhD in Physics in 2006 at the KULeuven in Belgium. In 2005 he joined Imecs pilot line as a support integration engineer, especially dealing with the process contamination control. He was part of the packaging group from end 2007 till begin 2010, working as a senior integration engineer dealing with 3D-stacked IC integration. From 2010 to 2019 he led the nano-applications and –material engineering (NAME) group at Imec. He (co-)authored more than 150 journal and conference papers and holds >40 Patents.

April 23 at 10.00 (CET): Frank Koppens

Stacking and twisting 2D materials for quantum nano-optoelectronics
ICFO – The Institute of Photonics Sciences,

Two-dimensional (2D) materials offer extraordinary potential for control of light and light-matter interactions at the atomic scale. In this talk, we will show a new toolbox to exploit the collective motion of light and charges as a probe for topological, hyperbolic and quantum phenomena.

We twist or nanostructure heterostructures of 2D materials that carry optical excitations such as excitons, plasmons or hyperbolic phonon polaritons. Nanoscale optical techniques such as near-field optical microscopy reveal with nanometer spatial resolution unique observations of topological domain wall boundaries, hyperbolic phononic cavities [1], and interband collective modes in charge-neutral twisted-bilayer graphene near the magic angle [2]. The freedom to engineer these so-called optical and electronic quantum metamaterials [3] is expected to expose a myriad of unexpected phenomena.

Intriguingly, we define nanoscale phonon polaritonic cavities, where the resonances are not associated with the eigenmodes of the cavity. Rather, they are multi-modal excitations whose reflection is greatly enhanced due to the interference of constituent modes. We will also show a new type of graphene-based magnetic-resonance that we use to realize single, nanometric-scale cavities of ultra-confined acoustic graphene plasmons [4]. We reach record-breaking mode volume confinement factors of  5 · 10−10. This AGP cavity acts as a Mid-infrared nanoantenna, which is efficiently excited from the far-field, and electrically tunable over an ultra-broadband spectrum.  Finally, we present near-unity light absorption in a monolayer WS2 van der Waals heterostructure cavity [5].

[1] Herzig Sheinfux et al., in preparation
[2] Hesp et al., Arxiv 1910.07893
[3] Song, Gabor  et. al., Nature Nanotechnology (2019)
[4] Epstein et al., Arxiv 2002.00366
[5] Epstein et al., Arxiv 1908.07598

Prof. Frank Koppens obtained his Ph.D. in experimental physics at Delft University, at the Kavli Institute of Nanoscience, The Netherlands.  After a postdoctoral fellowship at Harvard University, Since August 2010, Koppens is a group leader at the Institute of Photonic Sciences (ICFO).  The quantum nano-optoelectronics group of Prof. Koppens focuses on both science and technology of novel two-dimensional materials and quantum materials.  Prof. Koppens is vice-chairman of the executive board of the graphene flagship program, a 1000 Million Euro project for 10 years. He is also the leader of the optoelectronics work package within the flagship.  Prof. Koppens holds a GSMA Chair with activities related to the Mobile World Congress. Koppens has received five ERC awards: the ERC starting grant, the ERC consolidator grant, and three ERC proof-of-concept grants. Other awards include the Christiaan Hugyensprijs 2012, the national award for research in Spain, and the IUPAP young scientist prize in optics. In total, Koppens has published more than 70 refereed papers (H-index above 47), with more than 35 in Science and Nature family journals. Total citations >17.500 (google scholar).  

May 7 at 15.00 (CET): Sarah Haigh

Atomic Imaging enabling 2D heterostructure development: Studies of bend, twist, and point defects
University of Manchester

This talk aims to demonstrate how atomic resolution transmission electron microscope imaging is being used to support and enable the development of 2D materials and their heterostructures. The possibility to create new ‘designer’ materials by stacking together atomically thin layers extracted from layered materials with different properties has opened up a huge range of opportunities, from new optoelectronic phenomena [1], modifying and enhancing electron interactions in moire superlattices [2], to creating a totally new concept of designer nanochannels for molecular or ionic transport [3]. The impressive progress being achieved in the field crucially depends on knowledge of the atomic structure of these heterostructures, which in many cases can only be analysed by transmission electron microscopy (TEM) techniques. In this talk I will try to illustrate this statement with some of our recent work. For example, plan view imaging of point defect dynamics in graphene encapsulated monochalcogenides, GaSe and InSe (Fig. 2) [4]. 
Cross sectional imaging allows analysis and also prediction of the 
microstructures produced when 2D van der Waals material (graphite, boron nitride, MoSe2) are subjected to mechanical deformation [5]. We find that above a critical thickness the materials exhibit numerous twin boundaries and for large bend angles these can contain nanoscale regions of local delamination (Fig.1). Such features are proposed to be important in determining how easily the material can be thinned by mechanical or liquid exfoliation.[5] We finally demonstrate study of twisted bilayer structures of semiconducting transition metal chalcogenides where we see unexpected structural relaxation, different to that observed in bilayer graphene. Complementary scanning tunnelling measurements show that such reconstruction creates strong piezoelectric textures, opening a new avenue for engineering of 2D material properties [6].

[1] Zultak, Nature Communications 11 (1), 1-6 (2020)
[2] R. Krishna-Kumar, Science 357, 181-184 (2017)
[3] B. Radha et al. Nature 538, 222–225 (2016) and Keerthi, et al Nature 558 (7710), 420-424. (2018) 
[4] Hopkinson et al ASC Nano 13 (5), 5112-5123 (2019)
[5] Rooney et al 9, Nature Communications, 9, 3597, (2018)  
[6] Weston et al Nature Nanotechnology, in press (2020).

Sarah Haigh is Professor of Materials in the Department of Materials at University of Manchester, Director of the Electron Microscopy Centre (the largest in the UK), and Deputy Director of the BP International Centre for Advanced Materials. Her group applies advanced transmission electron microscopy (TEM) techniques to understand nanomaterial performance and she holds an ERC Starter Grant developing in situ TEM techniques with 2D heterostructures. 

May 14 at 16.00 (CEST): Mark Hersam

Atomically Thin Neuromorphic Computing Materials and Devices
Department of Materials Science and Engineering, Northwestern University, USA
2220 Campus Drive, Evanston, IL 60208-3108, USA;

The exponentially improving performance of conventional digital computers has slowed in recent years due to the speed and power consumption issues that are largely attributable to the von Neumann bottleneck (i.e., the need to transfer data between spatially separate processor and memory blocks). In contrast, neuromorphic (i.e., brain-like) computing aims to circumvent the limitations of von Neumann architectures by spatially co-locating processor and memory blocks or even combining logic and data storage functions within the same device. In addition to reducing power consumption in conventional computing, neuromorphic devices also provide efficient architectures for emerging applications such as image recognition, machine learning, and artificial intelligence [1]. With this motivation in mind, this talk will explore the opportunities for atomically thin materials in neuromorphic devices. For example, by combining p-type single-walled carbon nanotube thin films with n-type transition metal dichalcogenides, gate-tunable diodes have been realized, which show anti-ambipolar transfer characteristics that are suitable for artificial neurons, competitive learning, and spiking circuits [2]. In addition, by exploiting field-driven defect motion mediated by grain boundaries in monolayer MoS2, gate-tunable memristive phenomena have been achieved, which enable hybrid memristor/transistor devices (i.e., “memtransistors”) that concurrently provide logic and data storage functions [3]. The planar geometry of memtransistors further allows multiple contacts to the channel region that mimic the behavior of biological neurons such as heterosynaptic responses [4]. Overall, this work introduces new foundational circuit elements for neuromorphic computing in addition to providing alternative pathways for studying and utilizing the unique charge transport characteristics of atomically thin materials and heterostructures [5].

[1] V. K. Sangwan, et al., Nature Nanotechnology, DOI: 10.1038/s41565-020-0647-z (2020).
[2] M. E. Beck, et al., Nature Communications, 11, 1565 (2020).
[3] V. K. Sangwan, et al., Nature Nanotechnology, 10, 403 (2015).
[4] V. K. Sangwan, et al., Nature, 554, 500 (2018).
[5] D. Jariwala, et al., Nature Materials, 16, 170 (2017).

Mark C. Hersam is the Walter P. Murphy Professor of Materials Science and Engineering and Director of the Materials Research Center at Northwestern University. He also holds faculty appointments in the Departments of Chemistry, Applied Physics, Medicine, and Electrical Engineering. He earned a B.S. in Electrical Engineering from the University of Illinois at Urbana-Champaign (UIUC) in 1996, M.Phil. in Physics from the University of Cambridge (UK) in 1997, and a Ph.D. in Electrical Engineering from UIUC in 2000. His research interests include nanomaterials, nanomanufacturing, scanning probe microscopy, nanoelectronic devices, and renewable energy. Dr. Hersam has received several honors including the Presidential Early Career Award for Scientists and Engineers, TMS Robert Lansing Hardy Award, AVS Peter Mark Award, MRS Outstanding Young Investigator, U.S. Science Envoy, MacArthur Fellowship, and eight Teacher of the Year Awards. An elected member of the National Academy of Inventors, Dr. Hersam has founded two companies, NanoIntegris and Volexion, which are commercial suppliers of nanoelectronic and battery materials, respectively. Dr. Hersam is a Fellow of MRS, AVS, APS, AAAS, SPIE, and IEEE, and also serves as an Associate Editor of ACS Nano.