5 nm structures produced by direct laser writing

Abstract

Here we present a new approach to overcome the optical diffraction limit by using novel materials. In the paper, we report experimental results obtained by high-resolution transmission electron microscopy (HRTEM) and optical absorption spectroscopy, for a fluorescent photosensitive glass-ceramic containing rare-earth ions such as samarium (Sm). Using a home built dynamic tester, with a low power laser, we recorded nanostructures having 5 nm line widths. In the line structure, measurements reveal the presence of silver nanocrystals with few nanometre sizes. HRTEM shows that there is a random orientation of the nanocrystals. A writing mechanism with three steps is proposed.

Coherent exciton mechanism of three-dimensional quantum optical lithography

“…The transfer of energy from a lightharvesting system to a reaction center is a highly efficient process. Coherence could explain this efficiency.The aim of this paper is to propose a coherent exciton mechanism for quantum optical lithography, using our previous experimental studies [1,[7][8][9].A mixed quantum/classical approach for describing the confinement effect is examined. In the approach, only excitons are treated quantum mechanically, whereas an electric field is described in the classical way.…”

“…The aim of this paper is to propose a coherent exciton mechanism for quantum optical lithography, using our previous experimental studies [1,[7][8][9].…”

“…The nucleation and growth of silver nanocrystals as a 3D effect was realized by the following mechanism [8], with three steps: (i) local photo-excitation of the material, which generates photoelectrons; (ii) formation of neutral silver atoms Ag 0 as a result of trapping photoelectrons by silver ions Ag ; (iii) diffusion of mobile Ag 0 from the irradiated volume to the center of the laser beam, in order to grow stable silver nanocrystals. In the experimental conditions described in [2], λ 650 nm; P 100 nW; v 150 μ∕s; cylinder diameter 2 nm; and the absorbed energy per volume is 2.1 × 10 −13 J∕nm 3 and the number of absorbed photons per volume is 7 × 10 5 photons∕nm 3 .…”

“…In a three-photon process [1], the number of absorbed photons per volume is 88 photons∕nm 3 . High-resolution transmission electron microscopy (HRTEM) measurements [8] confirm that metallic Ag clusters have a face-centered-cubic (fcc) structure with an atomic density of 59 Ag atoms∕nm 3 , and the absorbed photon number per Ag atom needed to form one neutral Ag atom is 1.49.…”

“…In glass, Ag 0 atoms have high mobility even at room temperature [21,22], and stable silver nanocrystals [8] will be formed in the irradiated volume. Experimental results [9] obtained by transmission electron microscopy (TEM) measurements confirm a uniform spatial distribution of silver nanocrystals.…”