Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 90: Phase change / resistive switching (DS with HL)

HL 90.1: Vortrag

Donnerstag, 19. März 2015, 15:00–15:15, H 0111

Nanosecond laser-induced phase transitions in pulsed laser deposition-deposited GeTe films — •Xinxing Sun, Erik Thelander, Jürgen W. Gerlach, and Bernd Rauschenbach — Leibniz Institute of Surface Modification, Permoserstr. 15, D-04318, Leipzig, Germany

Phase changes in chalcogenide-based alloys have been widely studied in terms of the application in optical data storage and the same class of phase change materials is a promising candidate for further applications in non-volatile memories. In this study, phase transformations between the amorphous and crystalline state in GeTe thin films grown by pulsed laser deposition (PLD) are investigated. The phase transformations are induced by irradiation with nanosecond laser pulses at 248 nm and pulse duration of 20 ns. The structural and optical properties of the GeTe films were studied by x-ray diffraction and optical reflectivity measurements as a function of the number of irradiation pulses between 0 and 30 pulses and of the laser fluence up to 195 mJ/cm2. A reversible phase transition is found by using pulse numbers more than 5 pulses at a fluence above the threshold fluence for crystallization (between 11 and 14 mJ/cm2) and single pulse at a fluence of between 162 and 182 mJ/cm2 for amorphization. The influence of film thickness (6-300 nm) and irradiation with pulse repetition frequency (1-400 Hz) on the crystallization behavior of GeTe films is also discussed. A high optical contrast between the amorphous and crystalline state is achieved, proving that PLD-deposited GeTe films have excellent potential for application in phase change storage.