Indirect to direct band gap crossover in two-dimensional WS2(1−x)Se2x alloys

Abstract In atomically thin transition metal dichalcogenide semiconductors, there is a crossover from indirect to direct band gap as the thickness drops to one monolayer, which comes with a fast increase of the photoluminescence signal. Here, we show that for different alloy compositions of WS2(1−x)...

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Autores principales:	Cyrine Ernandes, Lama Khalil, Hela Almabrouk, Debora Pierucci, Biyuan Zheng, José Avila, Pavel Dudin, Julien Chaste, Fabrice Oehler, Marco Pala, Federico Bisti, Thibault Brulé, Emmanuel Lhuillier, Anlian Pan, Abdelkarim Ouerghi
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Materials of engineering and construction. Mechanics of materials TA401-492 Chemistry QD1-999
Acceso en línea:	https://doaj.org/article/4f5cee023c774f3f8aba36b5f4a4d72c
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spelling	oai:doaj.org-article:4f5cee023c774f3f8aba36b5f4a4d72c2021-12-02T13:35:39ZIndirect to direct band gap crossover in two-dimensional WS2(1−x)Se2x alloys10.1038/s41699-020-00187-92397-7132https://doaj.org/article/4f5cee023c774f3f8aba36b5f4a4d72c2021-01-01T00:00:00Zhttps://doi.org/10.1038/s41699-020-00187-9https://doaj.org/toc/2397-7132Abstract In atomically thin transition metal dichalcogenide semiconductors, there is a crossover from indirect to direct band gap as the thickness drops to one monolayer, which comes with a fast increase of the photoluminescence signal. Here, we show that for different alloy compositions of WS2(1−x)Se2x this trend may be significantly affected by the alloy content and we demonstrate that the sample with the highest Se ratio presents a strongly reduced effect. The highest micro-PL intensity is found for bilayer WS2(1−x)Se2x (x = 0.8) with a decrease of its maximum value by only a factor of 2 when passing from mono-layer to bi-layer. To better understand this factor and explore the layer-dependent band structure evolution of WS2(1−x)Se2x , we performed a nano-angle-resolved photoemission spectroscopy study coupled with first-principles calculations. We find that the high micro-PL value for bilayer WS2(1−x)Se2x (x = 0.8) is due to the overlay of direct and indirect optical transitions. This peculiar high PL intensity in WS2(1−x)Se2x opens the way for spectrally tunable light-emitting devices.Cyrine ErnandesLama KhalilHela AlmabroukDebora PierucciBiyuan ZhengJosé AvilaPavel DudinJulien ChasteFabrice OehlerMarco PalaFederico BistiThibault BruléEmmanuel LhuillierAnlian PanAbdelkarim OuerghiNature PortfolioarticleMaterials of engineering and construction. Mechanics of materialsTA401-492ChemistryQD1-999ENnpj 2D Materials and Applications, Vol 5, Iss 1, Pp 1-7 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Materials of engineering and construction. Mechanics of materials TA401-492 Chemistry QD1-999
spellingShingle	Materials of engineering and construction. Mechanics of materials TA401-492 Chemistry QD1-999 Cyrine Ernandes Lama Khalil Hela Almabrouk Debora Pierucci Biyuan Zheng José Avila Pavel Dudin Julien Chaste Fabrice Oehler Marco Pala Federico Bisti Thibault Brulé Emmanuel Lhuillier Anlian Pan Abdelkarim Ouerghi Indirect to direct band gap crossover in two-dimensional WS2(1−x)Se2x alloys
description	Abstract In atomically thin transition metal dichalcogenide semiconductors, there is a crossover from indirect to direct band gap as the thickness drops to one monolayer, which comes with a fast increase of the photoluminescence signal. Here, we show that for different alloy compositions of WS2(1−x)Se2x this trend may be significantly affected by the alloy content and we demonstrate that the sample with the highest Se ratio presents a strongly reduced effect. The highest micro-PL intensity is found for bilayer WS2(1−x)Se2x (x = 0.8) with a decrease of its maximum value by only a factor of 2 when passing from mono-layer to bi-layer. To better understand this factor and explore the layer-dependent band structure evolution of WS2(1−x)Se2x , we performed a nano-angle-resolved photoemission spectroscopy study coupled with first-principles calculations. We find that the high micro-PL value for bilayer WS2(1−x)Se2x (x = 0.8) is due to the overlay of direct and indirect optical transitions. This peculiar high PL intensity in WS2(1−x)Se2x opens the way for spectrally tunable light-emitting devices.
format	article
author	Cyrine Ernandes Lama Khalil Hela Almabrouk Debora Pierucci Biyuan Zheng José Avila Pavel Dudin Julien Chaste Fabrice Oehler Marco Pala Federico Bisti Thibault Brulé Emmanuel Lhuillier Anlian Pan Abdelkarim Ouerghi
author_facet	Cyrine Ernandes Lama Khalil Hela Almabrouk Debora Pierucci Biyuan Zheng José Avila Pavel Dudin Julien Chaste Fabrice Oehler Marco Pala Federico Bisti Thibault Brulé Emmanuel Lhuillier Anlian Pan Abdelkarim Ouerghi
author_sort	Cyrine Ernandes
title	Indirect to direct band gap crossover in two-dimensional WS2(1−x)Se2x alloys
title_short	Indirect to direct band gap crossover in two-dimensional WS2(1−x)Se2x alloys
title_full	Indirect to direct band gap crossover in two-dimensional WS2(1−x)Se2x alloys
title_fullStr	Indirect to direct band gap crossover in two-dimensional WS2(1−x)Se2x alloys
title_full_unstemmed	Indirect to direct band gap crossover in two-dimensional WS2(1−x)Se2x alloys
title_sort	indirect to direct band gap crossover in two-dimensional ws2(1−x)se2x alloys
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/4f5cee023c774f3f8aba36b5f4a4d72c
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Indirect to direct band gap crossover in two-dimensional WS2(1−x)Se2x alloys

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