Crystallization of Ge8Sb2‐xBixTe11 thin films employing single femtosecond pulses

0494423 - ÚFP 2019 RIV CZ eng O - Others
Karabyn, Vasyl - Tveryanovich, Y. S. - Bezdička, P. - Mistřík, J. - Knotek, P. - Wágner, T. - Frumar, M.
Crystallization of Ge8Sb2‐xBixTe11 thin films employing single femtosecond pulses.
2018
R&D Projects: GA MŠMT(CZ) LO1206
Institutional support: RVO:61389021
Keywords : phase transition * thin films * femtosecond laser * crystallization
OECD category: Inorganic and nuclear chemistry

Recently, phase transition driven by an ultrafast (femtosecond or picosecond) pulsed laser has attracted increasing attention in attempts to increase the speed of the phase change processes [1−4]. Optical recording was the first demonstrated in 1992 with using ultrashort laser pulses. The advantage of this technology is that ultrafast lasers have potentials to resolve the heat diffusion limitation of the conventiona laser recording, achieving high area recording densities. The phase transition of Ge 8 Sb 2-x Bi x Te 11 (were x=0, 1, 2) thin films from the amorphous phase into the crystalline phase induced by single femtosecond pulses of 800 nm and 40 fs has been studied. It was established the pulse energy window for crystallization in the thin films with thickness 100 nm prepared by Flash Thermal Evaporation (FE). The crystallization ofmarks written in amorphous background by single fs pulses were characterized using anoptical microscope AXIO ZEISS. The topology of shot point was observed by WLI and AFM. The phase transition induced by the single and double femtosecond shots in the active Ge 8 Sb 2-x Bi x Te 11 layer was examined using X-ray diffraction (XRD), which confirmed the crystalline structure of thin films after single fs shot. The reflectivity difference between the amorphous and laser-induced crystalline phases upon fs irradiation was investigated by WASE. The optical contrast for fs-irradiated films was more as 25 %, which is relatively high value for optical recording.
Permanent Link: http://hdl.handle.net/11104/0287989