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A combination of far-infrared and Raman spectroscopy is employed to investigate vibrational modes and the carrier behavior in amorphous and crystalline ordered GeTe-Sb 2 Te 3 alloys (GST) epitaxially grown on Si (111). The infrared active GST mode is not observed in the Raman spectra and vice versa, indication of the fact that inversion symmetry is preserved in the metastable cubic phase in accordance with the F m3 space group. For the trigonal phase, instead, a partial symmetry break due to Ge/Sb mixed anion layers is observed. By studying the crystallization process upon annealing with both the techniques, we identify temperature regions corresponding to the occurrence of different phases as well as the transition from one phase to the next. Activation energies of 0.43 eV and 0.08 eV for the electron conduction are obtained for both cubic and trigonal phases, respectively. In addition a metal-insulator …
Nature Publishing Group
Publication date: 
24 Jun 2016

V Bragaglia, K Holldack, JE Boschker, F Arciprete, E Zallo, T Flissikowski, R Calarco

Biblio References: 
Volume: 6 Issue: 1 Pages: 1-7
Scientific reports