Improved thermal stability and direct hexagonal transition accompanied by metal-insulator transition in Arsenic substituted Ge2Sb2Te5

Shekhawat, Roopali and Madhavan, Vinod Erkkara and Ramesh, K (2022) Improved thermal stability and direct hexagonal transition accompanied by metal-insulator transition in Arsenic substituted Ge2Sb2Te5. In: Journal of Alloys and Compounds, 910 . ISSN 09258388

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Abstract

Amorphous chalcogenides, particularly Ge2Sb2Te5 (GST) based alloys, are well known for their non-volatile phase-change random access memory applications (PCRAM). In this work, the phase change properties of Ge2Sb2−xAsxTe5 (x = 0, 0.5, 1.0, 2.0) thin films deposited by thermal evaporation are reported. The As substituted samples crystallize at higher temperatures compared to parent GST. During the phase change for x > 1.0, a direct transition from amorphous to the stable hexagonal structure has been observed. A distinct two-step transition in Sb rich samples and a single step transition for As rich samples are observed in R-T measurements with a high contrast in electrical resistivity. The transition is becoming sharper and sharper with increasing As substitution. A composition-dependent Metal-Insulator Transition (MIT) is also observed in these samples. Compared to GST, As substituted samples show an increase in crystallization temperature and activation energy for crystallization. For GST, the 10-year data retention temperature is 67 °C, and with complete As substitution, it increases to 169 °C, with a significant rise of 102 °C in the data retention temperature. High thermal stability, sharp transition and increased data retention of As substituted Ge-Sb-Te suggest that they are promising candidates for PCRAM applications.

Item Type:	Journal Article
Publication:	Journal of Alloys and Compounds
Publisher:	Elsevier Ltd
Additional Information:	The copyright of this article belongs to the Elsevier Ltd.
Keywords:	Amorphous materials; Data retention; Metal-insulator transition; Phase change memory; Phase transition; Vapor deposition
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	25 May 2022 04:26
Last Modified:	25 May 2022 04:26
URI:	https://eprints.iisc.ac.in/id/eprint/72322

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