Published the April 16, 2024

Indentation of a ternary 2D material membrane coupled with local optical measurement

Straintronics involves the manipulation and regulation of the electronic characteristics of 2D materials through the use of macro- and nano-scale strain engineering. In this study, an atomic force microscope (AFM) coupled with an optical system is used to perform indentation measurements and tip-enhanced photoluminescence (TEPL), allowing to extract the local optical response of a suspended monolayer membrane of ternary WSSe at various levels of deformation, up to strains of 10%. The photoluminescence signal is modeled considering the deformation, stress distribution, and strain dependence of the WSSe band structure. An additional TEPL signal is observed that exhibits significant variation under strain, with 64 meV per percent of elongation. This peak is linked to the highly strained 2D material lying right underneath the tip. The amplification of the signal and its relation to the excitonic funneling effect are discussed in a more comprehensive model. The diffusion caused by Auger recombination against the radiative excitonic decay will also be compared. TEPL is used to examine and comprehend the local physics of 2D semi-conducting materials subjected to extreme mechanical strain. Chemical vapor deposition-fabricated 2D ternaries possess high strain resistance, comparable to the benchmark MoS2, and a high Young's modulus of 273 GPa.

C2N's mat2D group is an expert in the electronic properties of 2D materials (Graphene, MX and MX2). Our activities focus on the design, fabrication and electronic properties of new hybrid heterostructures based on two-dimensional materials, with a view to realizing a new generation of nanoelectronic devices. This publication is made in collaboration with Hunan University, Polytechnique and Horiba.

Anis Chiout 1, Agnès Tempez 2, Thomas Carlier 2, Marc Chaigneau 2, Fabian Cadiz3, Alistair Rowe3, Biyuan Zheng 4, Anlian Pan4, Marco Pala 1, Fabrice Oehler 1, Abdelkarim Ouerghi 1, Julien Chaste 1*
High Strain Engineering of a Suspended WSSe Monolayer Membrane by Indentation and Measured by Tip-enhanced Photoluminescence

Advanced optical materials, April 2024

1 Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France.
2 HORIBA France SAS, Passage Jobin Yvon, 91120 Palaiseau, France
3 Laboratoire de Physique de la Matière Condensée, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France.
4 Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, and College of Materials Science and Engineering, Hunan University, 410082 Changsha, Hunan, China.

Contact : Julien Chaste

Figure 1 - Indentation of a ternary 2D membrane, a WSSe monolayer, coupled with optical measurement. (Left) a schematic of the experimental set-up (insert) a photo of the sample seen from above. (Right) TEPL signal measurements. The shoulder visible at lower energies comes from the area at the tip of the tip, which is highly mechanically stressed, with deformations of up to 10%. This signal varies strongly with strain, according to 64meV/% strain.