Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 113: 2D materials beyond graphene: TMDCs, silicene and relatives V

O 113.9: Talk

Friday, March 16, 2018, 12:30–12:45, MA 043

Nanoscale energy flow in 2D metal / 2D semiconductor heterostructures studied with femtosecond electron diffraction — •Thomas Vasileiadis, Daniela Zahn, Yingpeng Qi, and Ralph Ernstorfer — Fritz-Haber-Institut, Faradayweg 4-6, 14195 Berlin, Germany

Having techniques for studying energy flow mechanisms in systems with nanoscale heterogeneities is essential for the development of future nanodevices. This task can be carried out using femtosecond electron diffraction (FED), a technique in which the lattice response to electronic excitations is probed by ultrashort electron bunches [1]. In this talk we will present FED studies of a 2D metal / 2D semiconductor heterostructure. Our samples consist of exfoliated multilayer flakes of WSe₂ with epitaxially grown Au on their surface. WSe₂ in contact with nanostructured Au is a promising material for optoelectronics. As an example, a recent study reported 20,000-fold enhancement of photoluminescence [2]. For a deeper understanding of energy flow in this system we have studied the laser-induced vibrational excitation of the individual materials by means of the Debye-Waller effect. Our results show that decoration with Au has significant effect on the optical properties and lattice dynamics of WSe₂.

[1] L. Waldecker, R. Bertoni, R. Ernstorfer, J. Appl. Phys. 117, 044903 (2015).

[2] Z Wang, et al. Nature Communications 7, 11283 (2016).