PNNL

Abstract

Localized emission in atomically thin semiconductors have sparked significant interest as single photon sources. Despite comprehensive studies into the correlation between localized strain and exciton-emission, the impacts of charge transfer on nanobubble emission remains elusive. In this work, we report the observation of core/shell-like localized emission from monolayer WSe2 nanobubbles at room-temperature through near-field studies. We observe that by modifying the electronic junction between monolayer WSe2 and the Au substrate, one can effectively adjust the two-dimensional semiconductor to three-dimensional metal junction from Schottky to an Ohmic junction. Through concurrent analysis of topography, potential, tip-enhanced photoluminescence, and piezo response force microscope, we deduce that the core/shell-like emissions are attributed to strong piezoelectric potential aided by induced polarity at the WSe2-Au Schottky interface which results in spatial confinement of the excitons. Our findings present a new approach for manipulating charge confinement and engineering localized emission within atomically thin semiconductor nanobubbles. These insights hold implications for advancing the nano- and quantum photonics from low-dimensional semiconductors.