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SUMMARY:EXCITON MANIPULATION IN 2D SEMICONDUCTOR HETEROSTRUCTURES
DTSTART:20191004T151500
DTEND:20191004T161500
DTSTAMP:20261005T021959Z
UID:81a05a6c6016f314506ff2acdac120d85188b661b46d04cf59ae95cf
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof Andras Kis\, from Institute of Electrical Engineering EP
 FL Lausanne\nThe discovery of graphene marked the start of research in 2D 
 electronic materials which was expanded in new directions with MoS2 and ot
 her layered semiconducting materials. They have a wide range of interestin
 g fundamental properties and potential applications. New opportunities are
  enabled by the band structure of transition metal dichalcogenides (TMDCs)
  in which we could harness the valley degree of freedom for valleytronics 
 and next-generation photonics. Long-lived interlayer excitons in van der W
 aals heterostructures based on TMDCs have recently emerged as a promisin
 g platform for this\, allowing control over exciton diffusion length\, ene
 rgy and polarisation. I will show here how by using MoS2/WSe2 van der Waal
 s heterostructures\, we can realize excitonic transistors with switching a
 ction\, confinement and control over diffusion length at room temperature 
 in a reconfigurable potential landscape. On the other hand\, the weak inte
 rlayer interaction and small lattice mismatch in MoSe2/WSe2 heterostructur
 es results in brightening of forbidden optical transitions\, allowing us t
 o resolve two separate interlayer transitions with opposite helicities and
  meV-scale linewidths. These have opposite helicities under circularly pol
 arized excitation\, either preserving or reversing the polarization of inc
 oming light. By using externally applied electrical fields\, we can contro
 l their relative intensities and polarisation by different regions in the 
 moiré pattern\, characterized by different local symmetries and optical s
 election rules.\n \n \n \nReferences\n[1] A. Ciarrocchi\, D. Unuchek\, 
 A. Avsar\, K. Watanabe\, T. Taniguchi\, A. Kis. Nature Photonics 13\, 131
 –136 (2019).\n[2] D. Unuchek\, A. Ciarrocchi\, A. Avsar\, K. Watanabe\, 
 T. Taniguchi\, A. Kis. Room-Temperature Electrical Control of Exciton Flux
  in a van Der Waals Heterostructure. Nature 560\, 340–344 (2018).\n \n
  \n \n 
LOCATION:CE 1 5 https://plan.epfl.ch/?room==CE%201%205
STATUS:CONFIRMED
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