Structural, vibrational and electronic properties in the glass-crystal transition of thin films Sb70Te30 doped with Sn

BILOVOL, V.; FONTANA, M.; ROCCA, J.A.; CHANDUVÍ, H.H. MEDINA; NAVARRO, A.M. MUDARRA; REBAZA, A.V. GIL; ERRICO, L.A.; LIANG, A.; ERRANDONEA, D.; UREÑA, A.M.

JOURNAL OF ALLOYS AND COMPOUNDS

ELSEVIER SCIENCE SA

Año: 2020 vol. 845

0925-8388

Antimony-telluride based phase-change materials doped with Sn have been proposed to be ideal ma-terials for improving the performance of phase-change memories. It is well known that Sb 70 Te 30 thinfilms show a sharp fall in the electrical resistance in a narrow temperature range when heating.Therefore, it is interesting to study the effect of adding Sn into this composition. In this work, undopedand Sn-doped SbeTe thin films of composition Sn x [Sb 0.70 Te 0.30 ] 100-x , with x ¼ 0.0, 2.5, 5.0 and 7.5 at. %,have been obtained by pulsed laser deposition. Their electrical resistance has been measured whileheating from room temperature to 650 K. A sharp fall in the electrical resistance, associated to the glass-crystal transition, has been detected in all the samples within a narrow temperature range. The onsettemperature of this transformation increases with the Sn content. Both as-obtained and thermally-treated films have been structurally characterized by X-ray and by Raman spectroscopy. We havecompared the results among these compositions in terms of the identified crystallization products,transformation onset temperatures, transformation temperature ranges and amorphous/crystallizedelectrical resistance ratio. We have found that the frequency of the Raman modes decreases with Sn-doping. Finally, in order to study the electronic structure and to determine the band gap, the fre-quencies of the allowed Raman modes and the vibration directions of the Sb 70 Te 30 compound, DensityFunctional Theory based ab initio calculations have been performed as a function of the Sn concentration.