Quantum 2D materials

What we do
 

Phonon-photon-electron interactions in 2D materials

In 2D materials strain can be an effective tool to control the electronic Fermi surface topology and electron–phonon coupling. It has been applied to modify the optical properties of semiconducting transition metal dichalcogenides such as MoS2 or WS2. In MoS2 membranes reversible tuning of the optical band gap of suspended monolayer by as much as 500 meV have been reported. At the same time, coupled straintronic-photothermic effect, where coupling between bandgap of the 2D layered semiconductor under localized strains, optical absorption and the photo-thermal effect results in a large chromatic mechanical response.

Van de Waals materials, where 2D layers act as building blocks are expected to exhibit different properties than the constituent materials. These structures can be realized either by mechanical transfer or direct growth by means of chemical vapour deposition (CVD). The weak van der Waals bonding between the layers allows for them to slide, in fact MoS2 makes a perfect solid lubricant commonly used for industrial applications. But the nanoscale study of the interlayer coupling and strain transfer remains to be performed, especially focusing on the twisted angle between the layers.

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MoS2 grown on Si/SiO2 by CVD method.

 

Strain and fracture in 2D materials

Two-dimensional materials are potential candidates for flexible nanotechnology because of their unique physical and mechanical properties and their ease of transfer onto soft and plastic substrates that facilitate large-area flexible devices fabricated at a reasonable cost. One of the key requirements for flexible electronics is the ability of the active components to handle a reasonably high strain. Therefore, it has been crucial to exploit the properties of 2D materials to obtain properly functioning flexible devices.

 

Various fundamental questions arise on the actual performance of the 2D materials under strain: will their properties remain the same? How much strain is actually transferred from the flexible substrate to the 2D layer? And how much strain is transferred from one layer to another?

Within the Quantum 2D Materials Team we experimentally study the elastic properties of polycrystalline MoS2 films in the limit of very small grains and in two different grain morphologies. We investigate the critical strain of this material on different stretchable substrates, such as elastic tape and polydimethylsiloxane (PDMS) by scanning electron microscopy.

 

Moreover, we investigate the effect that electron beam exposure has on the MoS2/PDMS interface, as a means to increase the critical strain. Finally, we study the morphology and propagation of nanocracks forming in the MoS2 by TEM. The aim of this work is to explore strategies to enhance the

mechanical strength of 2D materials

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In-situ fracture of the polycrystaline Mos2 film.

 

2D materials for environmental sensing

One of the consequences of industrial development is the increased emission of different types of gases to the atmosphere. Some of these gases have a direct negative impact on human health (e.g., NO2 generated by industrial processes, CO emitted by cars, …), while others affect in a more indirect but long-term manner by impacting on the environment, which is the cause of climate change.

In the past decades gas sensors were mainly developed with materials such as metal oxides or ceramics due to their good mechanical and chemical stability and relatively fast response. In recent years new gas sensing materials are being considered, including graphene, black phosphorus, and transition metal dichalcogenides (TMDs). These materials are attractive for sensing applications because of their chemically active edges, easy-fabrication methods and good electrical performance. An added value of 2D materials is their potential for applications for flexible and wearable devices. Moreover, the sensing characteristics can be easily tunable by modifying its geometry and surface, functionalizing with molecules, decorating with metals or by combining with other 2D materials to create heterostructures.

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2D nanosheets-based humidity sensor

 

Our team

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Dr. Marianna
Sledzinska

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Peng
Xiao

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Dr. Emigdio
Chavez

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Dr. Francesc
Alzina

Selected publications

  1. Arrighi, Alois; del Corro, Elena; Navarro Urrios, Daniel; et al; Sledzinska, Marianna 2021. Heat dissipation in few-layer MoS2 and MoS2/hBN heterostructure 2D Materials. IOP Publishing. 9-1, pp.015005-015005.

  2. Xiao, Peng; Mencarelli, Davide; Chavez-Angel, Emigdio; Joseph, Christopher Hardly; Cataldo, Antonino; Pierantoni, Luca; Sotomayor Torres, Clivia M.; Sledzinska, Marianna. 2021. Reversing the Humidity Response of MoS2-and WS2-Based Sensors Using Transition-Metal Salts ACS Applied Materials & Interfaces. 13-19, pp.23201-23209.

  3. Sledzinska, Marianna (AC); Jumbert, Gil; Placidi, Marcel; Arrighi, Alois; Xiao, Peng; Alzina, Francesc; Sotomayor Torres, Clivia M. 2020. Fracturing of Polycrystalline MoS2 Nanofilms ACS Applied Electronic Materials. 2-4, pp.1169-1175

  4. Sledzinska, Marianna; Quey, Romain; Mortazavi, Bohayra; et al; Sotomayor Torres, Clivia M. 2017. Record Low Thermal Conductivity of Polycrystalline MoS2 Films: Tuning the Thermal Conductivity by Grain Orientation ACS Applied Materials & Interfaces. 9-43, pp.37905-37911.

 

Projects

  • MakIng New ElectRonic deVices from Amorphous materials (MINERVA), Flag-Era 2021

  • Artificial permittivity and permeability engineering for future generation sub-wavelength analogue integrated circuits and systems (NANOPOLY) GA 289061, FET-Open 2019

  • NANO components for electronic SMART wireless systems (NANOSMART) GA 825430, ICT 2019