Berlin 2024 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 54: 2D Materials IV: Graphene (joint session O/TT)

TT 54.7: Talk

Wednesday, March 20, 2024, 16:45–17:00, MA 005

Hyperlens enabled defect imaging in hBN-covered few-layer graphene — •Lina Jäckering, Konstantin G. Wirth, and Thomas Taubner — I. Institute of Physics (IA), RWTH Aachen University

Most of the unique phenomena of few-layer graphene (FLG) can only be observed when the FLG flake is encapsulated in hexagonal Boron Nitride (hBN) [1]. The fabrication process of encapsulated graphene devices can alter the stacking order and induce defects within the FLG flake [2]. The present stacking order and possible defects significantly influence the graphene sample’s electronic properties. Therefore, the visualization of stacking domains and defects in graphene flakes before, during, and after the fabrication of a transport device is of great interest. Here, we show that scanning near-field optical microscopy (s-SNOM) can visualize submicrometer-sized defects in FLG below 33 nm hBN. We attribute the achieved super-resolution imaging of buried defects to the hyberbolic nature of hBN [3]. hBN hosts hyperbolic phonon polaritons that enable super-resolution focusing through a cover layer of hBN, the so called hyperlensing effect [3]. Here, we present the first practical application of the hyperlensing effect in a hBN-FLG heterostructure. Our work paves the way for characterization of FLG devices during fabrication. [1] Dean et al. Nat. Nanotechnol. 5, 722 (2010). [2] Geisenhof et al. ACS Appl. Nano Mater. 2, 6067 (2019). [3] Li et al. Nat. Commun. 6, 7507 (2015).

Keywords: graphene; hBN; defect imaging; hyperlensing; s-SNOM