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Issue 47, 2018
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van der Waals interaction-induced photoluminescence weakening and multilayer growth in epitaxially aligned WS2

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Abstract

Recently, transition metal dichalcogenides (TMDCs) have attracted great interest due to their unique electronic and optical properties. Chemical vapor deposition (CVD) has been regarded as the most promising method for the synthesis of large-area TMDCs with high reproducibility. Having similar hexagonal crystal structures with many TMDCs, c-plane sapphire is commonly used as a growth substrate in CVD. However, few studies have been reported on the influence of the sapphire substrate on the growth behavior and physical properties of TMDCs. In this work, we demonstrate that higher strain is induced in epitaxially grown WS2 grains via van der Waals interactions with sapphire as compared with misaligned WS2 grains. In addition, this strain was found to enhance overlayer deposition on monolayer WS2, while multilayer growth was not observed in non-epitaxial WS2. Photoluminescence (PL) of the epitaxially grown WS2 grains was reduced, reflecting the effective van der Waals interaction with sapphire. Moreover, low-temperature PL measurements revealed strong influence of the c-plane sapphire surface on the optical properties of WS2. Density functional theory (DFT) calculation supports that the aligned WS2 grains are more strongly bound to the sapphire surface, as compared with misaligned WS2. Our work offers a new insight into the understanding of the influence of the substrate on the CVD-grown TMDC materials.

Graphical abstract: van der Waals interaction-induced photoluminescence weakening and multilayer growth in epitaxially aligned WS2

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Publication details

The article was received on 12 Jul 2018, accepted on 07 Nov 2018 and first published on 07 Nov 2018


Article type: Paper
DOI: 10.1039/C8CP04418J
Citation: Phys. Chem. Chem. Phys., 2018,20, 29790-29797

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    van der Waals interaction-induced photoluminescence weakening and multilayer growth in epitaxially aligned WS2

    H. G. Ji, M. Maruyama, A. S. Aji, S. Okada, K. Matsuda and H. Ago, Phys. Chem. Chem. Phys., 2018, 20, 29790
    DOI: 10.1039/C8CP04418J

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