Dresden 2014 – scientific programme

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DS: Fachverband Dünne Schichten

DS 44: Poster III: Focus session: Resistive switching by redox and phase change phenomena

DS 44.15: Poster

Thursday, April 3, 2014, 16:00–19:00, P1

Analysis of the switching behaviour of Phase Change Materials using s-SNOM — •Martin Lewin, Benedikt Hauer, Ann-Katrin U. Michel, and Thomas Taubner — Institute of Physics (IA), RWTH Aachen University, 52056 Aachen, Germany

Phase Change Materials (PCM) show at least two stable states in the solid phase: One amorphous and one crystalline state. These two states have significantly different dielectric functions. The fact that the two states can be switched reversibly by optical or electrical means (laser-, voltage-pulses) makes PCM very interesting for storage applications (Re-Writable-Discs, Phase-Change-RAM) or even logical photonic devices [1]. PCM are often characterised by TEM, AFM or far-field reflection measurements (diffraction-limited).

Scattering-type scanning near-field optical microscopy (s-SNOM) is based on an illuminated metal coated tip being scanned over a sample. The backscattered light is measured in a detector yielding the near-field optical amplitude and phase signals which depend on the dielectric function of the sample. Due to the local detecting approach the lateral resolution is no longer wavelength-dependent (here: approx. 25 nm). S-SNOM does not rely on thin samples as TEM does and yields subsurface information in contrast to AFM.

Here we present our progress in resolving the state of switched PCM (both thermally and by laser-pulse sequences) on a nm-scale using s-SNOM.

[1] Simone Raoux and Matthias Wuttig. In Nanoelectronics and Information Technology. Rainer Waser (ed.). Wiley-VCH Verlag, 2012.