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Plasmon-induced hot-electron generation for nanoscopy and spectroscopy.

Giugni A., Torre B., Allione M., Di Fabrizio E.
  Giovedì 14/09   16:00 - 19:00   Aula A224   II - Fisica della materia
The fields of plasmonics and nano-electronics have become a highly developed, advanced and differentiated science over the past two decades triggered by the disclosure of many fundamental scientific breakthroughs. New ideas have led to fascinating experimental results in many fields in physics, pushing to a new level the knowledge and the control of the processes that rule optoelectronic devices and life science at the nanoscale. Of paramount importance has been the comparison of results from complementary investigation techniques able to offer topographical, structural, chemical, magnetic, optical and electrical transport characterization of the samples at micro- and nanoscale as well as its interaction potentiality with the environment. We introduce the experimental setup recently developed for Hot Electron Nanoscopy and spectroscopy (HENs) that relies on an electric scanning probe microscope, a Raman spectrometer and a plasmonic device. From the optical point of view, the intrinsic electromechanical nature of surface plasmon polaritons is responsible for a local field enhancement that has opened the way to a spectroscopic analysis of the tiny amount of matter, down to the single-molecule detection limit. Taking advantage of the enhanced interaction of light with metallic nanostructures, we can generate of a sub-diffraction limited localization of the electromagnetic energy that overcomes both limits, the fundamental optical diffraction, and the energy transport of the electrons in the metal. It offers at the same time nanometric spatial resolution for topography, optical spectroscopy, and hot-electrons (he) nanoscopy. HENs has been used for the characterization innovative semiconductors for applications in electronics: 2D $MoS_{2}$ single crystal and a $p$-type $SnO$ layer. Results are supported by complementary scanning Kelvin probe microscopy, conductive AFM and Raman measurements. HENs reveals new features of local complexity in $MoS_{2}$ and poly-crystalline structure of $SnO$ at nanometric scale otherwise undetected.