Dresden 2017 – scientific programme
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DS: Fachverband Dünne Schichten
DS 13: Phase Change/Resistive Switching
DS 13.4: Talk
Monday, March 20, 2017, 15:45–16:00, CHE 91
Accurately controllable phase transitions in pulsed laser deposition-deposited GeTe films for multi-level memory applications — •Xinxing Sun1, Andriy Lotnyk1, Martin Ehrhardt1, Pierre Lorenz1, Jürgen W. Gerlach1, and Bernd Rauschenbach1,2 — 1Leibniz Institute of Surface Modification, Permoserstr. 15, D-04318, Leipzig, Germany — 2Institute for Experimental Physics II, Leipzig University, Linnéstr. 5, D-04103 Leipzig, Germany
Multi-level storage techniques are promising for increasing storage density and for reducing energy consumption in the application of phase-change materials based memory devices. However, accurately controlling the phase transitions as well as understanding the underlying switching mechanisms are still unsolved. In this study, non-volatile optical multi-level switching in single-layer GeTe phase-change films prepared by laser ablation are demonstrated to be feasible and accurately controllable at a timescale of nanoseconds. For this purpose, an ns UV laser pump-probe setup was adapted for the investigations. This system is capable to vary the laser parameters with broad ranges. Moreover, the optical switching process and the phase transformation are correlated on the microscopic scale for understanding of the switching mechanism. It is found that each 20 ns laser pulse (wavelength: 248 nm) with a fluence of 26 mJ/cm2 excitation induced a partial crystallization, and complete crystallization was achieved by a succession of 5 such pulses. In the reverse process, a single pulse excitation at a fluence of 112 mJ/cm2 leads to re-amorphization of the film.