@article{52d2d24abad74a72aa57e1ac070a6efe,
title = "Electrically Tunable and Dramatically Enhanced Valley-Polarized Emission of Monolayer WS2 at Room Temperature with Plasmonic Archimedes Spiral Nanostructures",
abstract = "Monolayer transition metal dichalcogenides (TMDs) have intrinsic valley degrees of freedom, making them appealing for exploiting valleytronic applications in information storage and processing. WS2 monolayer possesses two inequivalent valleys in the Brillouin zone, each valley coupling selectively with a circular polarization of light. The degree of valley polarization (DVP) under the excitation of circularly polarized light (CPL) is a parameter that determines the purity of valley polarized photoluminescence (PL) of monolayer WS2. Here efficient tailoring of valley-polarized PL from monolayer WS2 at room temperature (RT) through surface plasmon–exciton interactions with plasmonic Archimedes spiral (PAS) nanostructures is reported. The DVP of WS2 at RT can be enhanced from <5% to 40% and 50% by using 2 turns (2T) and 4 turns (4T) of PAS, respectively. Further enhancement and control of excitonic valley polarization is demonstrated by electrostatically doping monolayer WS2. For CPL on WS2–2TPAS heterostructures, the 40% valley polarization is enhanced to 70% by modulating the carrier doping via a backgate, which may be attributed to the screening of momentum-dependent long-range electron–hole exchange interactions. The manifestation of electrically tunable valley-polarized emission from WS2–PAS heterostructures presents a new strategy toward harnessing valley excitons for application in ultrathin valleytronic devices.",
author = "Lin, {Wei Hsiang} and Wu, {Pin Chieh} and Hamidreza Akbari and Rossman, {George R.} and Yeh, {Nai Chang} and Atwater, {Harry A.}",
note = "Funding Information: This work was jointly supported by the Army Research Office under the Multi-University Research Initiative (MURI) program (award #W911NF-16-1-0472) and the National Science Foundation under the Physics Frontier Center program for Institute for Quantum Information and Matter (IQIM) at the California Institute of Technology (award #1733907). The authors are also grateful for the support from the Beckman Institute at the California Institute of Technology for access to facilities at the Molecular Materials Research Center. W.-H.L. acknowledges a graduate fellowship from the J. Yang Family Foundation. P.C.W. acknowledges the support from the Ministry of Science and Technology (MOST), Taiwan (Grant number: 107-2923-M-006-004-MY3; 108-2112-M-006-021-MY3; 110-2124-M-006-004), and in part from the Higher Education Sprout Project of the Ministry of Education (MOE) to the Headquarters of University Advancement at National Cheng Kung University (NCKU). P.C.W. also acknowledges the support from the Ministry of Education (Yushan Young Scholar Program). The authors also thank Wen-Hui Cheng for training on the atomic layer deposition (ALD) system. Funding Information: This work was jointly supported by the Army Research Office under the Multi‐University Research Initiative (MURI) program (award #W911NF‐16‐1‐0472) and the National Science Foundation under the Physics Frontier Center program for Institute for Quantum Information and Matter (IQIM) at the California Institute of Technology (award #1733907). The authors are also grateful for the support from the Beckman Institute at the California Institute of Technology for access to facilities at the Molecular Materials Research Center. W.‐H.L. acknowledges a graduate fellowship from the J. Yang Family Foundation. P.C.W. acknowledges the support from the Ministry of Science and Technology (MOST), Taiwan (Grant number: 107‐2923‐M‐006‐004‐MY3; 108‐2112‐M‐006‐021‐MY3; 110‐2124‐M‐006‐004), and in part from the Higher Education Sprout Project of the Ministry of Education (MOE) to the Headquarters of University Advancement at National Cheng Kung University (NCKU). P.C.W. also acknowledges the support from the Ministry of Education (Yushan Young Scholar Program). The authors also thank Wen‐Hui Cheng for training on the atomic layer deposition (ALD) system. Publisher Copyright: {\textcopyright} 2021 Wiley-VCH GmbH",
year = "2022",
month = jan,
day = "20",
doi = "10.1002/adma.202104863",
language = "English",
volume = "34",
journal = "Advanced Materials",
issn = "0935-9648",
publisher = "Wiley-VCH Verlag",
number = "3",
}