Three-Dimensional Atomistic Tomography of W-Based Alloyed Two-Dimensional Transition Metal Dichalcogenides

Abstract

Increased interest in two-dimensional (2D) materials and heterostructures for use as components of electrical devices has led to the use of an atomically mixed phase between semiconducting and metallic transition metal dichalcogenides that exhibited enhanced interfacial characteristics. To understand the lattice structure and properties of 2D materials on the atomic scale, diverse characterization methods such as Raman spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and X-ray photoemission spectroscopy (XPS) have been applied. However, determination of the exact chemical distribution, which is a critical factor for the interfacial layer, was hindered by limitations of these typical methods. In this work, atom-probe tomography (APT) was introduced for the first time to analyze the three-dimensional atomic distribution and composition variation of the atomic-scale multilayered alloy structure W NbSe. Composition profiles and theoretical calculations for each atom demonstrated the reaction kinetics and stoichiometric inhomogeneity of the W NbSe layer. The role of the intermediate layer was investigated by fabrication of a WSe-based field-effect transistor. Introduction of W NbSe between metallic NbSe and semiconducting WSe layers resulted in improved charge transport with lowering of the contact barrier.

Ultrafast Photonics of Ternary RexNb(1–x)S2 in Fiber Lasers

“…Furthermore, these TTMCs have been predicted to be relatively stable owing to their low mixing free energy . Due to outstanding characteristics, TTMCs are regarded as extremely promising candidates for applications in ultrafast photonics and electronics . Theoretical calculations have shown that doping TMCs with group VII elements favors substitutional doping, rather than occupying interstitial and defect sites .…”

“…32 Due to outstanding characteristics, TTMCs are regarded as extremely promising candidates for applications in ultrafast photonics and electronics. 33 Theoretical calculations have shown that doping TMCs with group VII elements favors substitutional doping, rather than occupying interstitial and defect sites. 34 Furthermore, through the introduction of the Re element, 2D TTMCs reveal composition-tunable structural phase transitions and enhanced stability over time, which offer opportunities to study novel phenomena and expand the scope of their application.…”

Tribological characteristics of atomic-scale niobium diselenide grown via chemical vapor deposition

“…As a control group, exfoliated NbSe 2 flakes were prepared under ambient conditions by mechanically exfoliating bulk source materials onto SiO 2 /Si substrates, as previously reported. 30,34,50,51) The exfoliated NbSe 2 flakes were identified using optical microscopy [Fig. 1(a)].…”

“…Raman spectroscopy was conducted to characterize the atomic vibrational modes of the two differently prepared NbSe 2 samples. 30,34,51) Figure 1 presents the optical micrographs and Raman spectra for a selection of exfoliated NbSe 2 flakes and CVD-grown NbSe 2 . For the exfoliated flake in Fig.…”