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O: Fachverband Oberflächenphysik

O 23: Ultrafast Electron Dynamics at Surfaces and Interfaces III

O 23.10: Talk

Tuesday, March 19, 2024, 12:45–13:00, MA 041

Sub-picosecond photo-induced local distortion reduction in Sb₂Te chalcogenide phase-change material — •Zhipeng Huang¹, Xinxin Cheng², Hazem Daoud³, Wen-Xiong Song⁴, R. J. Dwayne Miller³, Klaus Sokolowski-Tinten¹, and R. Kramer Campen¹ — ¹Faculty of Physics and Center of Nanointegration (CENIDE), University of Duisburg-Essen, Duisburg, Germany — ²SLAC National Accelerator Laboratory — ³Departments of Chemistry and Physics, University of Toronto — ⁴Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences

Chalcogenide phase-change materials can be switched reversibly between a low resistive opaque crystalline phase and a high resistive transparent amorphous phase by heating, electrical or optical pulses with (sub-)nanosecond switching speed. Femtosecond laser excitation provides an ultrafast, energy-efficient way for precisely manipulating the optical, electronic and structural properties of these materials.

Here we present our ultrafast electron diffraction and femtosecond-resolved sum frequency generation spectroscopy studies on Sb₂Te material under femtosecond UV pulse irradiation. We observed a sub-picosecond photo-induced non-thermal structural change in the crystallized Sb₂Te sample. Through careful structural factor calculations, we quantified the structural change corresponding to Sb/Te atom movement along the [111] plane to a less-distorted local structure by coupling to the A1g coherent optical phonon mode.

Keywords: Ultrafast electron diffraction; Non-linear spectroscopy; Structural dynamics