Tunable strain and bandgap in subcritical-sized MoS2 nanobubbles

0576885 - ÚFCH JH 2024 RIV US eng J - Journal Article
Gastaldo, Michele - Varillas, Javier - Rodríguez Rodríguez, Álvaro - Velický, Matěj - Frank, Otakar - Kalbáč, Martin
Tunable strain and bandgap in subcritical-sized MoS2 nanobubbles.
NPJ 2D MATER APPL. Roč. 7, č. 1 (2023), č. článku 71. E-ISSN 2397-7132
R&D Projects: GA ČR(CZ) GX20-08633X; GA ČR(CZ) GA22-04408S
Institutional support: RVO:61388955
Keywords : Energy gap * Layered semiconductors * Molecular dynamics
OECD category: Physical chemistry
Impact factor: 9.7, year: 2022
Method of publishing: Open access

Nanobubbles naturally formed at the interface between 2D materials and their substrate are known to act as exciton recombination centers because of the reduced bandgap due to local strain, which in turn scales with the aspect ratio of the bubbles. The common understanding suggests that the aspect ratio is a universal constant independent of the bubble size. Here, by combining scanning tunneling microscopy and molecular dynamics, we show that the universal aspect ratio breaks down in MoS2 nanobubbles below a critical radius (≈10 nm), where the aspect ratio increases with increasing size. Accordingly, additional atomic-level analyses indicate that the strain increases from 3% to 6% in the sub-critical size range. Using scanning tunneling spectroscopy, we demonstrate that the bandgap decreases as a function of the size. Thus, tunable quantum emitters can be obtained in 2D semiconductors by controlling the radius of the nanobubbles.
Permanent Link: https://hdl.handle.net/11104/0346284