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AG Experimentelle Nanophysik

In der Arbeitsgruppe Experimentelle Nanophysik werden ultradünne 2D-Materialien mit Methoden der Oberflächenforschung präpariert und charakterisiert. Ausgehend vom prototypischen Graphen (Physiknobelpreis 2010), das aus einer monoatomaren Schicht Kohlenstoff besteht, sind in den letzten Jahren zahlreiche weitere Mitglieder dieser Materialklasse entdeckt worden. Theoretisch  sind sogar einige hundert verschiedene Materialien möglich, von denen allerdings nur sehr wenige bereits synthetisiert werden konnten.

Unsere wichtigste Untersuchungsmethode ist die Rastertunnelmikroskopie (STM), mit der atomare Auflösung erreicht werden kann. Wir präparieren fortgeschrittene 2D-Materialien wie Komposite aus Graphen und hexagonalem Bornitrit oder ultradünne Halbleiter wie MoS2 unter genau kontrollierten Bedingungen, und modifizieren diese Schichten gezielt, um z. B. eine Dotierung zu bewirken oder die Wechselwirkung mit potenziell störenden Gasen aus der Umgebung zu untersuchen. In den letzten Jahren konnten wir so unter anderem zeigen, dass man Elektronen in Quantenpunkten aus Graphen einsperren kann, in welcher Form Graphen durch den Beschuss mit energetischen Ionen beschädigt wird, und wie es Fremdatome schaffen, zwischen 2D-Materialien und ihre Unterlage zu kriechen (Interkalation).

Neueste Nachrichten / Latest News

27.11.2021 Dany successfullly passed her PhD-defense. Congratulations, Dr. Dombrowski!


9.11.2021 Our paper "Structure of 2H-TaS2 on Au(111)" was published by Physical Review B. It  contains a detailed characterisation of the geometry of the system derived by X-ray standing waves (XSW), corroborated by density functional theory calculations (DFT). Authors are C. Silva, D. Dombrowski, A. Samad, J. Cai, W. Jolie, J. Hall, P. T. P. Ryan, P. Thakur, D. A. Duncan, T.-L. Lee, U. Schwingenschlögl, and C. Busse.

 

XSW_TaS2


3.11.2021 We submitted the manuscript "Spatial variation of geometry, binding, and electronic properties in the moiré superstructure of MoS2 on Au(111)" to 2D Materials. Authors are C.  C. Silva, D. Dombrowski, Nicolae Atodiresei, W. Jolie, F. Farwick zum Hagen, J. Cai, P. T. P. Ryan, P. Thakur, V. Casiuc, S. Blügel, D. A. Duncan, T. Michely, T.-L. Lee, and C. Busse.

Moire_2DM_2021


27.10.2021 Carsten Busse was elected as chairman of the Department of Physics.



18.10.2021 Our manuscript "Electronic structure of quasi-freestanding WS2/MoS2 heterostructures" has been published in by ACS Applied Materials & Interfaces. In this work, we study the band alignement at heterojunctions between two-dimensional semiconductors using STS. Authors are Borna Pielic, Dino Novko, Iva S’rut Rakic, Jiaqi Cai, Marin Petrovic, Robin Ohmann, Natasa Vujicic, Mario Basletic, Carsten Busse, and Marko Kralj.

 MoS2_heterostructure


5.10.2021 Catherine Grover started the research phase of her Master studies in our research group. She will work n ultrathin semiconductors. Welcome!


 

 2.10.2021 High-school students in 9th grade can now lear something about atomic structure using STM-images taken by our NaioSTM as an example.

 STM_Schulbuch


30.9.2021 Daniel Kurz submitted his Master thesis "Präparation und Rastertunnelmikroskopie von Vanadiumsulfiden unter Ultrahochvakuumbedingungen". Good job!

29.9.2021 We have submitte a manuscript "Metal-insulator transition in monolayer MoS2 via contactless chemical doping" to ACS Nano. Here, we describe how we can dope an ultrathin semiconductor by placing donors or acceptors close by.Authors are C. van Efferen, C. Murray, J. Fischer, C. Busse, H.-P. Komsa, T. Michely and W. Jolie.


22.9.2021 We returned from our first group retreat in Freusburg.

Freusburg2021


27.8.2021 Physical Review B accepted our paper "Sub-Poissonian distribution of Cs and K ions in the valleys of hBN/Ru(0001)" by Jiaqi Cai, Robin Ohmann, and Carsten Busse. Here, we demonstrate that alkali metal atoms adsorbed on hexagonal boron nitride show a more even distribution as expected by simple statistics, caused by the mutual Coulomb repulsion.

Sub-Poissonian


1.8.2021 Dr.Thaís Chagas Peixoto Silva (re-)joined the group as a postoc to investigate phase engineering in two-dimensional transition metal dichalcogenides. Welcome!
23.7.2021 Our paper "Two Phases of Monolayer Tantalum Sulfide on Au(111)" is published in ACS Nano. In this work, we describe a novel sulfur poor phase of tantalum sulfide on Au(111). Authors are Daniela Dombrowski, Abdus Samad, Clifford Murray, Marin Petrovic, Pascal Ewen, Thomas Michely, Marco Kralj, Udo Schwingenschlögl and Carsten Busse. 

gtoc


19.5.2021 Jiaqi Cai successfully defended his thesis as the last step in his PhD. Congratulations, Dr. Cai!

3.5.2021 Sammer Iqbal handed in his thesis  “Preparation of 2-D Group-IV Monochalcogenides” as the last step of his Master degree in Nanoscience and Nanotechnology. Well done!


15.2.2021 Muhammad Ali Martuza joined the group. He works on the preparation of 2D-materials for advanced characterization methods.


 9.11.2020 Alice Bremerich started the research phase of her Master studies with a project on ultrathin MoS2-WS2-junctions 


6.10.2020 Daniel Kurz joined the group to work on lateral TMDC heterostructures.

5.10.2020 Sammer Iqbal started his master thesis on the preparation of 2D group-IV monochalcogenides.


5.3.2020 Our paper "Sulfur structures on bare and graphene-covered Ir(111)" has been published in Journal of Physical Chemistry C.  Here, we describe a novel and very dense structure of a sulfur layer intercalated between graphene and its substrate. Authors are B. Pielic, J. Hall, V. Despoja, I. Srut Rakic, M. Petrovic, A. Sohani, C. Busse, T. Michely and M. Kralj. 


14.1.2020 Caio Silva successfully defended his thesis as the final step in obtaining the Dr. rer. nat. Congratulations!


15.11.2019 Madad Abbasli joined the group to work on his PhD-thesis "Epitaxially Grown Tin Perovskites".

17.10.2019 Veronika Blecker presented the main findings of her Bachelor's thesis "Pyrit als Schwefelquelle in der physikalischen Gasphasendeposition". Good job!

15.10.2019 Kai Mehlich started his PhD-thesis on ultrathin transition metal dichalcogenides.


1.10.2019 Dina Wilks joined the group as a masters student.


21.9.2019 Kai Mehlich presented his main findings in a talk "In plane heterostructures in transition metal dichalcogenides" as the final step of his M. Sc. in Physics. Congratulations!


9.9.2019 Alice Bremerich handed in her Bachelor's thesis "Inbetriebnahme eines Auger Spektrometers". Well done!


8.5.2019 Our paper "Lifting Epitaxial Graphene by Intercalation of Alkali Metals" was published in J. Phys. Chem. C. We have precisely determined the structure of intercalated graphene and find that already a small amount of Lithium is sufficient to fully delaminate graphene from Ir(111). Authors are C. C. Silva, J. Cai, W. Jolie, D. Dombrowski, F. H. Farwick zum Hagen, A. J. Martínez-Galera, C. Schlueter, T.-L. Lee and C. Busse.


29.4.2019 Veronika Blecker joined our group. She will establish evaporation of sulfur from FeS2 for the growth of ultrathin films.


 April 2019 Our new VT-STM from Scienta Omicron arrived and got installed.

VT-STM


01.04.2019 We welcome Alice Bremerich as a new group member. In her Bachelorthesis, she will use Auger electron spectroscopy (AES) to characterize surfaces especially 2D materials.


28.3.2019 Our paper "Tomonaga-Luttinger liquid in a box: Electrons confined within MoS2 mirror-twin boundaries" was published in Physical Review X. Here, we observe spin-charge separation in one-dimensional wires. Authors are W. Jolie, C. Murray, P. S. Weiß, J. Hall, F. Portner, N. Atodiresei, A. V. Krasheninnikov, C. Busse, H.-P. Komsa, A. Rosch und T. Michely.


26.3.2019 Our paper "Comprehensive tunneling spectroscopy of quasi-freestanding MoS2 on graphene on Ir(111)" was published in Phys. Rev. B. Here, we use a combination of different modes of scanning tunneling spectroscopy (STS) to reveal the band gap of MoS2 as well as additional critical point energies in the band structure. Authors are C. Murray, W. Jolie, J. A. Fischer, J. Hall, C. van Efferen, N. Ehlen, A. Grüneis, C. Busse, and T. Michely.


15.3.2019 We welcome Paulus Aleksa as a new group member. In his PhD-thesis, he will investigate two-dimensional ferroelectric materials.
12.3.2019 Our paper "Charge density wave phase of VSe2"  was published in Phys. Rev. B. In this work we use scanning tunneling spectroscopy (STS) to investigate the change in the electronic structure of VSe2 induced by correlated electrons. Authors are W. Jolie, T. Knispel, N. Ehlen, K. Nikonov, C. Busse, A. Grüneis and T. Michely.
8.1.2019 Our scanning tunneling microscope "TuMA 3" arrived from Münster.

28.11.2018 Our paper "Modifying the geometric and electronic structure of hexagonal boron nitride on Ir(111) by Cs adsorption and intercalation" was published in Phys. Rev. B.  Here, we show how the geometric and electronic properties of the ultrathin insulator hBN can me tuned by interacion with the electron donor Cs. Authors are J. Cai, W. Jolie, C. Silva, M. Petrovic, C. Schlueter, T. Michely, M. Kralj, T.-L. Lee, and C. Busse.


6.11.2018 New Member: Thaís Chagas joins the group.


30.10.2018 Joshua Fuhrmann successfully completed his Bachelor thesis: Aufbau eines Rastertunnelmikroskops unter Umgebungsbedingungen


9.10.2018 Dina Wilks successfully completed her Bachelor thesis: Elektrochemischer Transfer von Graphen und hexagonalem Bornitrid


29.8.2018 Our paper "Resonance Raman Spectrum of Doped Epitaxial Graphene at the Lifshitz Transition" was published in Nano Letters. Authors are M. G. Hell, N. Ehlen, B. V. Senkovskiy, E. H. Hasdeo, A. Fedorov, D. Dombrowski, C. Busse, T. Michely, G. di Santo, L. Petaccia, R. Saito, and  A. Grüneis. Here, we employ ultra-high vacuum (UHV) Raman spectroscopy in tandem with angle-resolved photoemission

(ARPES) to investigate the doping-dependent Raman spectrum of epitaxial graphene on Ir(111).


20.7.2018 Our paper "Valleys and hills of graphene on Ru(0001)" was published in J. Phys. Chem. C. In this work, we precisely determine the shape of a single layer of graphene using X-ray Standing Waves and find a good match to results from Density Functional Theory. Authors are C. Silva, M. Iannuzzi, D. Duncan,P. Ryan, K. Clarke, J. Küchle, J. Cai, W. Jolie, C. Schlueter, T.-L. Lee, and C: Busse
04.06.2018  New Members: Joshua Fuhrmann and Dina Wilks join the group.
01.05.2018  New Member: Dr. Robin Ohmann joins the group.
16.04.2018  New Member: Dennis Rybakowski joins the group.

08.03.2018  Our paper "Suppression of quasiparticle scattering signals in bilayer graphene due to layer polarization and destructive interference" was published in Phys. Rev. Lett. In this work, we demonstrate that electrons in bilayer graphene can be localized in one of the two layers only.
Graphene_bilayer_teaser

 19.01.2018 Our paper "Molecular beam epitaxy of quasi-freestanding transition metal disulphide monolayers on van der Waals substrates: a growth sstudy" was published in 2D Materials. In this work, we describe a new approach to grow transition metal dichalcogenides on top of graphene and hexagonal boron nitride.


 01.11.2017   The formation of our new group was featured in Siegener Zeitung (SZ) and  Westfalenpost (WP) (see also  the university's news).