Revealing Excitonic Complexes in Monolayer WS2 on Talc Dielectric

Author(s)

Prando, Gabriela Augusta ^[1] ; Severijnen, Marion E. ^{[2, 3]} ; Barcelos, Ingrid D. ^[4] ; Zeitler, Uli ^{[2, 3]} ; Christianen, Peter C. M. ^{[2, 3]} ; Withers, Freddie ^[5] ; Gobato, Yara Galvao ^{[3, 1]}

Affiliation

^[1] Univ Fed Sao Carlos, Phys Dept, Sao Carlos - Brazil

^[2] Radboud Univ Nijmegen, Inst Mol & Mat, NL-6525 AJ Nijmegen - Netherlands

^[3] Radboud Univ Nijmegen, High Field Magnet Lab HFML EMFL, NL-6525 ED Nijmegen - Netherlands

^[4] Brazilian Ctr Res Energy & Mat CNPEM, Brazilian Synchrotron Light Lab LNLS, BR-13083970 Campinas, SP - Brazil

^[5] Univ Exeter, Coll Engn Math & Phys Sci, Exeter EX4 4QF, Devon - England

• Document type: Journal article
• Source: PHYSICAL REVIEW APPLIED; v. 16, n. 6 DEC 23 2021.
• Web of Science Citations: 0

Abstract

We report on a detailed study of low-temperature photoluminescence (PL) and magnetophotoluminescence under perpendicular magnetic fields (up to 30 T) and circularly polarized excitation on high-quality monolayer (ML) WS2 on a thick layer (120 nm) of talc dielectric. Remarkably, we obtained high-quality samples without any evidence of localized exciton emission at low temperature and a PL linewidth comparable to that of WS2/h-BN samples. As a consequence, we observe well-resolved emission peaks at low temperature due to the formation of excitonic complexes, including a dark-trion (DT) state and phonon replicas of the DT without the application of an in-plane magnetic field. The nature of the emission peaks, the magnetic field dependence of the degree of polarization, and g factors are discussed in detail and compared with the corresponding results obtained for h-BN encapsulated transition-metal dichalcogenide (TMD) samples. We observe that under sigma(+)-polarized excitation the sign of the circular polarization of biexcitons is reversed under higher magnetic fields. In addition, the dark-trion polarization increases considerably with increasing perpendicular magnetic field, demonstrating different behavior compared with previous studies of dark trions on monolayer WSe2. Our results suggest that talc is indeed a promising layered material for the surface protection of ML TMDs and to explore fundamental physics in view of applications in optoelectronic devices. (AU)

• FAPESP's process: 19/23488-5 - 2D devices for optoeletronics
• Grantee: Yara Galvão Gobato
• Support Opportunities: Regular Research Grants
• FAPESP's process: 18/01808-5 - Optical and Transport Properties in High Magnetic Fields of Semiconductor Heterostructures and Devices based on Two Dimensional Materials
• Grantee: Yara Galvão Gobato
• Support Opportunities: Scholarships abroad - Research
• FAPESP's process: 18/00823-0 - New topological states of matter under extreme conditions
• Grantee: Ricardo Donizeth dos Reis
• Support Opportunities: Research Grants - Young Investigators Grants