Tip‐Induced Nano‐Engineering of Strain, Bandgap, and Exciton Funneling in 2D Semiconductors. Issue 17 (11th March 2021)

• Record Type: Journal Article
• Authors: Koo, Yeonjeong; Kim, Yongchul; Choi, Soo Ho; Lee, Hyeongwoo; Choi, Jinseong; Lee, Dong Yun; Kang, Mingu; Lee, Hyun Seok; Kim, Ki Kang; Lee, Geunsik; Park, Kyoung‐Duck
• Is Part Of: Advanced materials. Volume 33:Issue 17(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-03-11
• Subjects: exciton funneling -- strain‐engineering -- tip‐enhanced photoluminescence spectroscopy -- transition metal dichalcogenide monolayer -- wrinkle; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202008234
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: The tunability of the bandgap, absorption and emission energies, photoluminescence (PL) quantum yield, exciton transport, and energy transfer in transition metal dichalcogenide (TMD) monolayers provides a new class of functions for a wide range of ultrathin photonic devices. Recent strain‐engineering approaches have enabled to tune some of these properties, yet dynamic control at the nanoscale with real‐time and ‐space characterizations remains a challenge. Here, a dynamic nano‐mechanical strain‐engineering of naturally‐formed wrinkles in a WSe2 monolayer, with real‐time investigation of nano‐spectroscopic properties is demonstrated using hyperspectral adaptive tip‐enhanced PL ( a ‐TEPL) spectroscopy. First, nanoscale wrinkles are characterized through hyperspectral a ‐TEPL nano‐imaging with <15 nm spatial resolution, which reveals the modified nano‐excitonic properties by the induced tensile strain at the wrinkle apex, for example, an increase in the quantum yield due to the exciton funneling, decrease in PL energy up to ≈10 meV, and a symmetry change in the TEPL spectra caused by the reconfigured electronic bandstructure. Then the local strain is dynamically engineered by pressing and releasing the wrinkle apex through an atomic force tip control. This nano‐mechanical strain‐engineering allows to tune the exciton dynamics and emission properties at the nanoscale in a reversible fashion. In addition, a systematic switching and modulation platform of the wrinkle emission is demonstrated, which provides a new strategy for robust, tunable, and ultracompact nano‐optical sources in atomically thin semiconductors. Abstract : A dynamic nanomechanical strain‐engineering of naturally formed wrinkles in a WSe2 monolayer, with real‐time investigation of nano‐spectroscopic properties is demonstrated using hyperspectral adaptive tip‐enhanced PL ( a ‐TEPL) spectroscopy with <15 nm spatial resolution. This nanomechanical strain‐engineering allows tuning of the exciton dynamics and emission properties at the nanoscale. Furthermore, a systematic switching and modulation platform of the wrinkle emission is demonstrated.