Electrical switching and aluminium speciation in Al-As-Te glasses

Pumlianmunga, Pumlianmunga and Ramesh, K (2016) Electrical switching and aluminium speciation in Al-As-Te glasses. In: JOURNAL OF NON-CRYSTALLINE SOLIDS, 452 . pp. 253-258.

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Abstract

Bulk AlxAs30Te70-x glasses in the range 5 <= x <= 20 prepared by melt quenching method has been found to exhibit memory for x < 10 and threshold switching for x >= 10. Upon heating in a differential scanning calorimeter (DSC), glasses with x <= 10 show crystallization reaction whereas glasses with x> 10 do not show crystallization reaction. Glasses with x <= 10 crystallized into Te and As2Te3 crystal structures when annealed at their crystallization temperature. Glasses with x >= 15 crystallized to As2Te3 structure only. The glasses cooled from its melting temperature (T-m) in water at room temperature (28 degrees C) solidified into crystalline structure for x = 5, whereas x >= 10 solidified into amorphous structure. Magic angle spinning nuclear magnetic resonance (MAS NMR) results show Al-27 resides in Al-4] and Al-6] coordination. Raman spectra of the as-quenched, SET and RESET samples of the memory glass reveal that the SET state is crystalline and RESET state is amorphous. Raman spectra of threshold switching glass reveal no structural change even after 50 switching cycles. The progressive addition of Al promotes the transfer of lone-pair electrons of Te to AI atoms. We propose this lone-pair tailoring by Al may form a band above the valence band that decreases the density of charge carriers. As a result, a decrease in threshold current (Ith) and an increase in threshold voltage (Vth) is observed. The higher coordinated Al cross links the structural network heavily. This makes structural reorganization difficult resulting in the observed threshold switching in AlxAs30Te70-x for glasses with x > 5. (C) 2016 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	JOURNAL OF NON-CRYSTALLINE SOLIDS
Additional Information:	Copy right for this article belongs to the ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	30 Dec 2016 07:15
Last Modified:	30 Dec 2016 07:15
URI:	http://eprints.iisc.ac.in/id/eprint/55640

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