title: Nanoscale mapping of excitonic processes in single-layer MoS2 using tip-enhanced photoluminescence microscopy.
abstract: In two-dimensional (2D) semiconductors, photoluminescence originating from recombination processes involving neutral electron-hole pairs (excitons) and charged complexes (trions) is strongly affected by the localized charge transfer due to inhomogeneous interactions with the local environment and surface defects. Herein, we demonstrate the first nanoscale mapping of excitons and trions in single-layer MoS2 using the full spectral information obtained via tip-enhanced photoluminescence (TEPL) microscopy along with tip-enhanced Raman spectroscopy (TERS) imaging of a 2D flake. Finally, we show the mapping of the PL quenching centre in single-layer MoS2 with an unprecedented spatial resolution of 20 nm. In addition, our research shows that unlike in aperture-scanning near field microscopy, preferential exciton emission mapping at the nanoscale using TEPL and Raman mapping using TERS can be obtained simultaneously using this method that can be used to correlate the structural and excitonic properties.
authors.affiliation: Institute of Materials Physics, Hangzhou Dianzi University, 310018, Hangzhou, China and Key Laboratory of RF Circuits and Systems (Hangzhou Dianzi University), Ministry of Education of China, China.
authors.forename: Weitao
authors.initials: W
authors.lastname: Su
authors.affiliation: National Physical Laboratory, Hampton Road, Teddington, Middlesex, TW11 0LW, UK. debdulal.roy@npl.co.uk.
authors.forename: Naresh
authors.initials: N
authors.lastname: Kumar
authors.affiliation: National Physical Laboratory, Hampton Road, Teddington, Middlesex, TW11 0LW, UK. debdulal.roy@npl.co.uk.
authors.forename: Sandro
authors.initials: S
authors.lastname: Mignuzzi
authors.affiliation: National Physical Laboratory, Hampton Road, Teddington, Middlesex, TW11 0LW, UK. debdulal.roy@npl.co.uk and School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK.
authors.forename: Jason
authors.initials: J
authors.lastname: Crain
authors.affiliation: National Physical Laboratory, Hampton Road, Teddington, Middlesex, TW11 0LW, UK. debdulal.roy@npl.co.uk.
authors.forename: Debdulal
authors.initials: D
authors.lastname: Roy