A combination of far-infrared and Raman spectroscopy is employed to investigate vibrational modes and the carrier behavior in amorphous and crystalline ordered GeTe-Sb2Te3 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 Fm3 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 transition is clearly identified to occur at the onset of the transition between the disordered and the ordered cubic phase.

Bragaglia, V., Holldack, K., Boschker, J., Arciprete, F., Zallo, E., Flissikowski, T., et al. (2016). Far-Infrared and Raman Spectroscopy Investigation of Phonon Modes in Amorphous and Crystalline Epitaxial GeTe-Sb2 Te3 Alloys. SCIENTIFIC REPORTS, 6, 28560 [10.1038/srep28560].

Far-Infrared and Raman Spectroscopy Investigation of Phonon Modes in Amorphous and Crystalline Epitaxial GeTe-Sb2 Te3 Alloys

ARCIPRETE, FABRIZIO;
2016

Abstract

A combination of far-infrared and Raman spectroscopy is employed to investigate vibrational modes and the carrier behavior in amorphous and crystalline ordered GeTe-Sb2Te3 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 Fm3 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 transition is clearly identified to occur at the onset of the transition between the disordered and the ordered cubic phase.
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore FIS/03 - Fisica della Materia
English
Con Impact Factor ISI
PHASE-CHANGE MATERIALS; FILMS; GETE; TRANSITION; SUBSTRATE; SURFACE; METAL
Bragaglia, V., Holldack, K., Boschker, J., Arciprete, F., Zallo, E., Flissikowski, T., et al. (2016). Far-Infrared and Raman Spectroscopy Investigation of Phonon Modes in Amorphous and Crystalline Epitaxial GeTe-Sb2 Te3 Alloys. SCIENTIFIC REPORTS, 6, 28560 [10.1038/srep28560].
Bragaglia, V; Holldack, K; Boschker, J; Arciprete, F; Zallo, E; Flissikowski, T; Calarco, R
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/159776
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