Chemical vapor transport synthesis of a selenium-based two-dimensional material

Authors : Talip Serkan KASIRGA

Pages : 293-301

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Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :Selenium-based layered materials, and in particular transition-metal diselenides insert ignore into journalissuearticles values(TMDSs);, have intriguing properties in the monolayer limit. Materials such as MoSe 2 ` role=`presentation`> 2 2 _{2} , WSe 2 ` role=`presentation`> 2 2 _{2} , and NbSe 2 ` role=`presentation`> 2 2 _{2} display striking features such as spin-valley coupling at the valence-band edges and offer great potential for optoelectronics applications. Although a dozen of other TMDSs have been realized or proposed, whether two-dimensional chalcogens are possible or not is still an open challenge. In this work, we show the chemical vapor transport synthesis of a novel, atomically thin selenium-based material on oxidized silicon substrates. This new member of the two-dimensional materials family has a unique Raman spectrum similar to that of bulk selenium and has an optical gap of ∼ ` role=`presentation`> ∼ ∼ \sim 1.57 eV at room temperature determined by the photoluminescence. No transition metals are found in the stoichiometry of the crystals. Analysis of high-resolution transmission electron micrographs of the monolayers reveals a distinctive set of hexagonal spots indicating a sixfold symmetry of the lattice. Atomic force microscopy measurements show the monolayer thickness to be ∼ ` role=`presentation`> ∼ ∼ \sim 0.75 nm.
Keywords : Selenium based monolayer, 2D materials, chemical vapor transport, atomically thin materials