Nanoscopy of 2D materials

General public Colloquium / Congress / Forum

The simplicity and versatility of optical microscopy make it from the start the workhorse technique in the characterization of 2D materials (1). Optical microscopy is used to locate and determine the thickness of the 2D material by measuring its optical contrast with respect to the Si/SiO2 substrate (2). Although in terms of technology, the large-area growth of 2D materials is about to be mastered soon, as-grown 2D materials still host abundant and different types of defects such as vacancies, adatoms, grain boundaries (GBs), edges, and impurities, which strongly influence their properties (3). In most cases, the presence of defects is disadvantageous. However, not all defects in 2D materials are detrimental. Some 2D materials have been shown to host defects that can serve as single-photon emitters (SPEs) at cryogenic temperatures for TMDs (4-7) and room temperature for h-BN (8). This discovery has motivated the search for single-photon sources in other 2D materials and efforts that aim to engineer the defects in well-controlled locations either using strain- induced potential traps (9) or via quantum dot confinement (7). The advent of single quantum emitters in 2D materials offers new opportunities to construct a scalable quantum architecture. Transmission electron microscopy TEM, SPM or confocal microscopy techniques are not ideal for fast, high-throughput, in-situ imaging of defects in 2D materials with nanometer resolution. There is a clear demand for the development of advanced optical technology that images individual defects at better temporal, spectral and spatial resolutions. We have explored the single molecule localization microscopy to characterize defects in hexagonal boron nitride (10). In addition to precise location of the optically active defects we record as well their spectral properties using spectral SMLM (11).

speaker Prof. Aleksandra Radenovic
Laboratory of Nanoscale Biology
Institute of Bioengineering, EPFL, Lausanne
Contact Prof. Ana Akrap