B5 Investigating the influence of defects on charge carrier properties in resistive switching with near-field optical microscopy and spectroscopy

Project B5 (2019-2023) aims on the nanoscale imaging of conduction properties in electrical switching devices and materials of both types (PCM and VCM) in order to understand the fundamental defect-related mechanisms limiting their reliability and scalability. Specifically, we employ the imaging method of infrared scattering-type near-field optical microcopy (s-SNOM) to get quantitative information on the local charge carrier density in the proximity of defects or switched areas at nanoscale resolution. Besides the in situ imaging of filaments and dislocations in electrical switching devices, we will also address fundamental material and growth questions on chemically synthesized nanoparticles.


Near-field optical mapping and quantification of conduction properties in resistive switching

This project focuses on the nanoscale imaging of conduction properties and defects in various kinds of nanostructures capable of resistive switching. We employ and further develop high resolution imaging with infrared near-field optical microcopy (s-SNOM) to get quantitative information, e.g. on the local charge carrier density of single nanostructures or memory cells. This direct visualization will help to compare and improve different fabrication processes of resistively switching structures and lead to a better understanding of the underlying physics of the switching process.


Nano-optical mapping of conduction channels in resistive switching

In resistive switching, the local structure such as defects is key for device operation: For example, in valence change (VC) materials tiny conducting channels between the electrodes form below the surface. In contrast to other projects which perform a characterisation of memory cell materials, this project optically monitors the switching process of working devices by employing nanoscale infrared imaging methods. New imaging concepts based on infrared scanning-near-field optical microscopy (IR s-SNOM) are being developed and employed, aiming at nondestructive characterization of the local crystalline structure of phase change materials and at the mapping of subsurface of conductive channels within a memory device at nanoscale resolution.

Principal investigator:

Prof. Dr. rer. nat. T. Taubner
I. Physikalisches Institut IA
RWTH Aachen University
Phone: +49 (0)241 80 20260
E-mail: taubner@physik.rwth-aachen.de