Super-resolved discrimination of nanoscale defects in low-dimensional materials by near-field photoluminescence spectral imaging

Abstract

Low-dimensional materials (LDMs), such as monolayer transition-metal dichalcogenides, have emerged as candidate materials for next-generation optoelectronics devices. Detection of the spatial heterogeneity caused by various nanoscale defects in LDMs, is crucial for their applications. Here, we report the super-resolved discrimination of various nanoscale defects in LDMs by near-field photoluminescence (NFPL) spectral imaging of LDMs with scanning near-field optical microscopy. As a demonstration example, a monolayer WS2 sample is characterized with a sub-diffraction spatial resolution of 140 nm in ambient environment. By performing topography and NFPL mapping, different defects, such as the stacks, bubbles, and wrinkles, can be identified through their light emission properties, which strongly correlate with the exciton emission modulation and tensile strain arising from local structural deformations.