Fig. 5
From: Recent progress of exciton transport in two-dimensional semiconductors
a (i) Illustration of TEPL spectroscopy probing nanoscale wrinkle in WSe\(_2\) monolayer. Topography profile revealing a nanoscale wrinkle (ii), and its corresponding TEPL spectra obtained at the wrinkle site (iii). (iv) TEPL spectra acquired as the tip pressed against and released from the apex of the nanoscale wrinkle. Reversible control of TEPL energy (v) and intensity (vi) by changing tip position, i.e., pressure on the wrinkle apex. b (i) Illustration depicting a WSe\(_2\) monolayer transferred onto a nanogap structure, investigated using TEPL spectroscopy. Topography image showing the surface morphology of the WSe\(_2\) monolayer on the nanogap structure (ii), accompanied by corresponding TEPL intensity mapping (iii). (iv) Illustration demonstrating tip-induced modification of strain gradient within the WSe\(_2\) monolayer region near the nanogap structure. (v) Reversible control of TEPL intensity facilitated by dynamic control of tip position. (vi) Estimated strain gradient for suspended WSe\(_2\) monolayer on nanogap. (vii) Theoretical estimation of exciton distribution under microscale strain gradient (black curve) and nanoscale strain gradient (red curve). a Reproduced with permission [69]. Copyright [2021] John Wiley and Sons. b Reproduced with permission [70]. Copyright [2022] AAAS