2D Materials

LATEST NEWS

April 2016: Two Marie Sklodowska-Curie researchers have started in the group: Luca Sortino and Alessandro Catanzaro. The positions are funded by the new Marie Sklodowska-Curie Innovative Training Network ‘Spin-NANO’ coordinated by Sheffield.

December 2015: The group has expanded into a new lab fully dedicated to optics of 2D materials providing ample space for development of micro-Raman and micro-absorption techniques.

November 2015:  Our paper ‘WSe2 Light-Emitting Tunneling Transistors with Enhanced Brightness at Room Temperature’ has been published in Nano Letters.

October 2015: Our paper ‘Exciton–polaritons in van der Waals heterostructures embedded in tunable microcavities’ has been published in Nature Communications: Nature Communications 6, Article number: 8579 doi:10.1038/ncomms9579. 

September 2015: Three Sheffield’s Masters students joined the group: Lokesh Gurung, Catherine Phillips and David Draper.

August 2015: The group acquired a so-called ‘2D film transfer system’ from Manchester’s spin-off Graphene Industries designed for layer-by-layer assembly of van der Waals  heterostructures. First Sheffield-made MoSe2/hBN heterostructures giving exceptionally bright photoluminescence were produced by Evgeny Alexeev.

July 2015: Our paper ‘Photoluminescence of two-dimensional gallium chalcogenide films’ has been published in the journal 2D Materials (IoP): 2D Materials, 2 (3), 035010 (2015).

See more in the news archive below.

Overview

Open cavity set-up

Stefan aligning the open cavity set-up.

The isolation of single-atomic layer graphene has led to a surge of interest in other layered crystals with strong in-plane bonds and weak, van der Waals-like, interlayer coupling. Here we research new properties of two-dimensional chalcogenides (sulfides, selenides, and tellurides) such as MoS2, MoSe2, WSe2, NbSe2, gallium and indium chalcogenides, germanium chalcogenides and others from the huge family of these synthesized and natural materials. In their bulk form chalcogenides may vary from insulators to semiconductors, from metals to superconductors, and exhibit topological insulator properties. We obtain 2D films by mechanical exfoliation from layered van-der-Waals-bonded bulk crystals. The properties of 2D films may differ from the bulk quite dramatically. For example, some indirect band-gap semiconductors turn to direct band-gap ones and become optically active. Our recent effort is on development of hybrid photonic devices comprising these 2D films (see our latest paper in Nano Letters), including electrically pumped van der Waals heterostructures.

Mirror design and calculated electric field distribution in an open-access microcavity used for experiments with 2D films and heterostructures. The 2D structures are placed on the bottom dielectric mirror. The top mirror has a concave shape and can be positioned at a precise vertical displacement from the bottom mirror.

Mirror design and calculated electric field distribution in an open-access microcavity used for experiments with 2D films and heterostructures. The 2D structures are placed on the bottom dielectric mirror. The top mirror has a concave shape and can be positioned at a precise vertical displacement from the bottom mirror.

People

The group is led by Prof Sasha Tartakovskii. From September 2015 the group consists of 3 PhD students, Robert Schofield, Oleksandr Skrypka, Thomas Lyons, and 4 postdocs, Tillmann Godde, Scott Dufferwiel, Evgeny Alexeev, and Stefan Schwarz. We are expecting further expansion of the group with 3 PhD positions. We are the ‘most international’ research group at the department of Physics and Astronomy. In the group photo below taken in summer 2014 7 people with the origin from 7 countries from 3 continents are pictured including Russia (Sasha), Turkey (Hakan, MSc), Mexico (Osvaldo), Germany (Tillmann), UK (Robert), China (Le, summer student) and Austria (Stefan). Further geographical addition to the group in the last year is Ukraine (Oleksandr).

Outside the lab on a sunny day: Sasha, Hakan, Osvaldo, Tillmann, Robert, Le, Stefan (picture by Freddie Withers, Manchester)

Outside the lab on a sunny day (summer 2014): Sasha, Hakan, Osvaldo, Tillmann, Robert, Le, Stefan (picture by Freddie Withers, Manchester)

Resources

Osvaldo is aligning the angle-resolved micro-PL set-up to measure first microcavities with 2D films

Osvaldo is aligning the angle-resolved micro-PL set-up to measure first microcavities with 2D films

Prof Tartakovskii is an expert in photonics and magneto-optics of nano-structured semiconductors. He recently started new activities in optics of 2D materials. The group has a dedicated high-spec optical laboratory (including a state-of-the-art magneto-optics set-up), and shares access to several other state-of-the-art optics laboratories of Prof M Skolnick’s group. Sample and device fabrication is usually carried out at the National III-V Semiconductor Facility in Sheffield, with additional capabilities now available next door to our lab space. The group is quickly gaining confidence in fabrication and optics experiments on these materials. Recently, we acquired so-called ‘transfer system’ from a Manchester’s spin-out Graphene Industries. Evgeny Alexeev with the help of the company installed this system in the III-V Centre clean room in July 2015 and already in August 2015 produced first hBN/MoSe2 heterostructures giving bright PL.

Collaborations

Freddie Withers (our collaborator from Prof Novoselov's group in Manchester) and Osvaldo are installing a new van der Waals heterostructure LED sample in the cryostat. The picture is taken in the Sheffield's lab, where Freddie has been a frequent visitor since autumn 2013.

Freddie Withers (our collaborator from Prof Novoselov’s group in Manchester) and Osvaldo are installing a new van der Waals heterostructure LED sample in the cryostat. The picture is taken in the Sheffield’s lab, where Freddie has been a frequent visitor since autumn 2013.

Our main collaborators in this field are Prof K Novoselov’s group in Manchester (joint work on optics of van der Waals heterostructures). We also continue our close collaboration with a leading theorist in the field of 2D materials Prof V Falko (the Director of the National Graphene Institute in Manchester from October 2015). Other important collaborations include:leading ultra-fast optical spectroscopy group of Prof M Bayer/Prof D Yakovlev/Dr I Akimov (Dortmund); specialist in tunable optical microcavities Dr J Smith (Oxford); dielectric coating specialist Helia Photonics (Livingston); low-temperature positioning specialist Attocube Systems (Munich). Our collaborations with crystal growth groups include Dr N Kolesnikov (Chernogolovka) and Dr A Dmitriev (Kiev).

News-archive

June 2015: Our paper on stability of gallium and indium chalcogenides films has appeared on arxiv: http://arxiv.org/abs/1506.05619.

May 2015: Our paper on ‘Exciton-polaritons in van der Waals heterostructures embedded in tunable microcavities’ has appeared on arxiv: http://arxiv.org/abs/1505.04438.

May 2015: Proposal for a new Marie Sklodowska-Curie Innovative Training Network ‘Spin-NANO’ led by A. Tartakovskii has been successful.

April 2015: a new postdoctoral fellow Dr Evgeny Alexeev has been appointed to boost our micro-fabrication efforts. He will start in June 2015.

February 2015: Our paper on 2D LEDs (in collaboration with F Withers and K Novoselov, Manchester) has just been published: http://www.nature.com/nmat/…/nmat4205.html.

See also:
News and Views article
Sheffield’s press release
Manchester’s press release

January 2015: Our new paper entitled ‘Optical properties of two-dimensional gallium chalcogenide films’ has appeared on arxiv: http://arxiv.org/abs/1501.02214.

January 2015: Scott Dufferwiel joined the group as a postdoctoral researcher on our Graphene Flagship project.

December 2014: We have been awarded an EPSRC grant (collaboration with Prof A Patane, Nottingham) to investigate optical properties of layered III-VI materials.  We will be recruiting 2 postdocs, one with a focus on fabrication, and the other to do advanced optics experiments.

December 2014: Our joint paper with Prof K Novoselov’s group (Manchester) entitled ‘Light-emitting diodes by bandstructure engineering in van der Waals heterostructures’ has appeared on arxiv: http://arxiv.org/abs/1412.7621.

November 2014: Our paper on 2D semiconductors in tunable cavities has just been published online in Nano Letters  http://pubs.acs.org/doi/abs/10.1021/nl503312x. See a ‘Tech Update’ piece on this work at nanotechweb.org.

November 2014: Three master students have joined our group.

October 2014: A new PhD student Oleksandr Skrypka joined the group. He has arrived from Ukraine. He will work on 2D photonics including the latest microcavity projects.

June 2014: Sheffield’s group is joining the Graphene Flagship

Recent publications

2015

2014

2013

gmaili.net gmail.com login problems with gmail account and sign in tips