University of PardubiceFaculty of Chemical Technology

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Physico-Chemical properties of the Ge8Sb2−xBixTe11 bulks and thin films

Authors: Karabyn Vasyl | Přikryl Jan | Střižík Lukáš | Beneš Ludvík | Svoboda Roman | Frumarová Božena | Wágner Tomáš | Frumar Miloslav

Year: 2016

Type of publication: ostatní - přednáška nebo poster

Page from-to: nestránkováno

Titles:

Language	Name	Abstract	Keywords
eng	Physico-Chemical properties of the Ge8Sb2−xBixTe11 bulks and thin films	Materials based on ternary tellurides have been intensively studied for optical and electrical non-volatile memories such as DVD, Blu-ray and PRAM. In our study we focus on the Ge8Sb2−xBixTe11, where x = (0;0.02;0.1;0.2;1;1.8;2). Thin films (thickness ≈200 nm) were prepared by flash thermal evaporation (FE) and by pulsed laser deposition (PLD) techniques. Structure of all as-deposited (amorphous) and annealed (crystalline) films was investigated by X-ray diffraction analysis. The bulks crystallize into cubic rock salt structure of the Fm−3m space group with lattice parameter α ≈ 6 Å. In the case of bulk was observed Hexagonal phase P−3m1 was observed only in samples with x = (1;1.8;2). The activation energy of crystallization Eac was determined by Kissinger method. The electrical sheet resistance Rs of as-deposited thin films was measured by four-probe method according to van der Pauw. The difference of Rs between amorphous (108-105 Ω/sqr.) and crystalline (103-102 Ω/sqr.) was found to be 2–5 orders of magnitude. The electrical sheet resistance of all as-deposited (amorphous) thin films slightly decreases with increasing temperature according to Arrhenius relation. The refractive index of as-deposited PLD films was higher than that one of FE films. This feature can be attributed to higher density of PLD films in comparison with the FE films. Substitution of Sb by Bi leads to increase of refractive index which can be explained on the basis of Clausius-Mossotti equation. The optical contrast of the studied materials was found to be more than 20 % which indicates their applicability for phase-change memories.	thermal evaporation; pulsed laser deposition; non-volatile memories; phase-change memories; Ge-Sb-Te; Ge-Bi-Te; chalcogenides