Local structure of amorphous Ag5In5Sb60Te30 and In3SbTe2 phase change materials revealed by X-ray photoelectron and Raman spectroscopic studies

Sahu, Smriti and Manivannan, Anbarasu and Shaik, Habibuddin and Rao, Mohan G (2017) Local structure of amorphous Ag5In5Sb60Te30 and In3SbTe2 phase change materials revealed by X-ray photoelectron and Raman spectroscopic studies. In: JOURNAL OF APPLIED PHYSICS, 122 (1).

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Abstract

Reversible switching between highly resistive (binary ``0'') amorphous phase and low resistive (binary ``1'') crystalline phase of chalcogenide-based Phase Change Materials is accredited for the development of next generation high-speed, non-volatile, data storage applications. The doped Sb-Te based materials have shown enhanced electrical/optical properties, compared to Ge-Sb-Te family for high-speed memory devices. We report here the local atomic structure of as-deposited amorphous Ag5In5Sb60Te30 (AIST) and In3SbTe2 (IST) phase change materials using X-ray photoelectron and Raman spectroscopic studies. Although AIST and IST materials show identical crystallization behavior, they differ distinctly in their crystallization temperatures. Our experimental results demonstrate that the local environment of In remains identical in the amorphous phase of both AIST and IST material, irrespective of its atomic fraction. In bonds with Sb (similar to 44%) and Te (similar to 56%), thereby forming the primary matrix in IST with a very few Sb-Te bonds. Sb2Te constructs the base matrix for AIST (similar to 63%) along with few Sb-Sb bonds. Furthermore, an interesting assimilation of the role of small-scale dopants such as Ag and In in AIST, reveals rare bonds between themselves, while showing selective substitution in the vicinity of Sb and Te. This results in increased electronegativity difference, and consequently, the bond strength is recognized as the factor rendering stability in amorphous AIST. Published by AIP Publishing.

Item Type:	Journal Article
Publication:	JOURNAL OF APPLIED PHYSICS
Additional Information:	Copy right for this article belongs to the AMER INST PHYSICS, 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA
Department/Centre:	Division of Physical & Mathematical Sciences > Instrumentation Appiled Physics
Date Deposited:	29 Jul 2017 07:28
Last Modified:	29 Jul 2017 07:28
URI:	http://eprints.iisc.ac.in/id/eprint/57498

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