Effect of supercooling on the microstructural development and optimization of physical properties of melt grown SnSe crystals

Kunjomana, A G and Bibin, J and Karthikeyan, R and Varadharajaperumal, Santanu (2019) Effect of supercooling on the microstructural development and optimization of physical properties of melt grown SnSe crystals. In: JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS, 30 (15). pp. 14300-14311.

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Abstract

The microstructural development of stoichiometric tin monoselenide (SnSe) crystals grown by vertical Bridgman-Stockbarger method using an indigenously fabricated furnace has been investigated under high vacuum (similar to 10(-6) mbar). The ampoule translation rate (t(r)) and supercooling, Delta T (= T-m - T, where T-m is the melting point and T is the crystallization temperature) were varied in the range, 12-2 mm/h and 20-100 degrees C respectively. Enhancement of Delta T and t(r) led to constitutional supercooling, inducing compositional changes and non-stoichiometry. Low Delta T (20-40 degrees C) and high t(r) (12-10 mm/h) resulted in globules, flakes and cavities. When Delta T = 60 degrees C and t(r) = 9 to 7 mm/h, mounds were formed with closed contours and ripples, due to atomically rough liquid-solid (l-beta) interface. Fine tuning of Delta T (60 degrees C) and t(r) (2 mm/h) enabled smooth planar interface, so as to yield good quality crystalline structures with periodic atomic deposition promoting crystal growth, layer-by-layer. Energy dispersive analysis by X-rays and powder X-ray diffraction studies revealed appreciable crystallinity, chemical homogeneity and phase purity. The density of crystals estimated from crystallographic data (6.183 g/cm(3)) corroborates with that obtained utilizing Archimedes principle. Thermogravimetric and microindentation analyses established thermal and mechanical stability. The low etch pit density (similar to 10(2) cm(-2)) manifests nearly perfect growth of crystals than their melt counterparts. UV-Vis-NIR and PL spectra reflected direct transition with an energy gap of 1.32 eV, validating immense potential of the grown crystals for photovoltaic applications.

Item Type:	Journal Article
Publication:	JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
Publisher:	SPRINGER
Additional Information:	copyright for this article belongs to SPRINGER
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	12 Sep 2019 11:33
Last Modified:	12 Sep 2019 11:33
URI:	http://eprints.iisc.ac.in/id/eprint/63485

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