Substrate induced tuning of compressive strain and phonon modes in large area MoS2 and WS2 van der Waals epitaxial thin films

Sahu, Rajib and Radhakrishnan, Dhanya and Vishal, Badri and Negi, Devendra Singh and Sil, Anomitra and Narayana, Chandrabhas and Datta, Ranjan (2017) Substrate induced tuning of compressive strain and phonon modes in large area MoS2 and WS2 van der Waals epitaxial thin films. In: JOURNAL OF CRYSTAL GROWTH, 470 . pp. 51-57.

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Abstract

Large area MoS2 and WS2 van der Waals epitaxial thin films with control over number of layers including monolayer is grown by pulsed laser deposition utilizing slower growth kinetics. The films grown on c-plane sapphire show stiffening of A(1g) and E-2g(1) phonon modes with decreasing number of layers for both MoS2 and WS2. The observed stiffening translate into the compressive strain of 0.52% & 0.53% with accompanying increase in fundamental direct band gap to 1.74 and 1.68 eV for monolayer MoS2 and WS2, respectively. The strain decays with the number of layers. HRTEM imaging directly reveals the nature of atomic registry of van der Waals layers with the substrate and the associated compressive strain. The results demonstrate a practical route to stabilize and engineer strain for this class of material over large area device fabrication. (C) 2017 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	JOURNAL OF CRYSTAL GROWTH
Additional Information:	Copy right for this article belongs to the ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	12 Aug 2017 04:51
Last Modified:	12 Aug 2017 04:51
URI:	http://eprints.iisc.ac.in/id/eprint/57608

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