Browsing by Subject "Atomically thin materials"

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    Atomically thin materials
    (Springer, 2020) Kasırga, T. Serkan
    In this chapter, I will provide a brief overview of atomically thin materials that are formed by layers held together by van der Waals forces or weak covalent bonding. These materials provide a unique and cheap way of studying plethora of phenomena. Perhaps, the relative simplicity of the methods that are commonly used in the studies of two dimensional (2D) materials are one of the main reasons why they attracted attention at this level since the advent of graphene. After an introduction to the properties of 2D materials, I will talk about the methods to obtain 2D materials and conclude the chapter with the possibilities of heterostructures of 2D materials.
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    Chemical vapor transport synthesis of a selenium-based two-dimensional material
    (TÜBITAK, 2018) Kasırga, Talip Serkan
    Selenium-based layered materials, and in particular transition-metal diselenides (TMDSs), have intriguing properties in the monolayer limit. Materials such as MoSe2, WSe2, and NbSe2 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 ∼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 ∼0.75 nm.