Nanoscale Mapping and Defect‐Assisted Manipulation of Surface Plasmon Resonances in 2D Bi2Te3/Sb2Te3 In‐Plane Heterostructures. Issue 10 (24th March 2022) - Moradifar, Parivash
Abstract: The Bi2 Te3 /Sb2 Te3 in‐plane heterostructure is reported as a low‐dimensional tunable chalcogenide well suited as plasmonic building block for the visible−UV spectral range. Electron‐driven plasmon excitations of low‐dimensional Bi2 Te3 /Sb2 Te3 are investigated by monochromated electron energy loss spectroscopy spectrum imaging. To resolve the nanoscale spatial distribution of various local plasmonic resonances, singular value decomposition is used to disentangle the spectral data and identify the individual spectral contributions of various corner, edge, and face modes. Furthermore, defect‐plasmon interactions are investigated both for nanoscale intrinsic and thermally induced extrinsic polygonal defects (in situ sublimation). Signature of defect‐induced red shift ranging from a several hundreds of millielectronvolts to a few electronvolts, broadening of various plasmon response, together with selective enhancement and significant variations in their intensity are detected. This study highlights the presence of a heterointerface and identifies defects as physical tuning pathways to modulate the plasmonic response over a broad spectral range. Finally, the experimental observations are compared qualitatively and validated with numerical simulations using the electron‐driven discrete dipole approximation. Low‐dimensional Bi2 Te3 /Sb2 Te3 as a less explored plasmonic system holds great promises as emerging platform for integrated plasmonics. Furthermore, introducing controlled structural defects can open the door for nanoengineering of plasmonic properties in such systems. Abstract : This study highlights the electron‐driven plasmonic resonances with varying spatial distribution and identifies the physical and chemical tuning pathways in a plasmonic Bi2 Te3 /Sb2 Te3 heterostructure. Defect−plasmon interactions are investigated for nanoscale intrinsic and thermally induced extrinsic polygonal defects. Signature of defect‐induced red shift, broadening of various plasmon response, together with selective enhancement and significant variations in their intensity are detected.