Dinh Loc Duong⧫ 교수

Since graphene became available by a scotch tape technique, a vast class of two-dimensional (2D) van der Waals (vdW) layered materials has been researched intensively. What is more intriguing is that the well-known physics and chemistry of three-dimensional (3D) bulk materials are often irrelevant, revealing exotic phenomena in 2D vdW materials. By further constructing heterostructures of these materials in the planar and vertical directions, which can be easily achieved via simple exfoliation t

We present a density functional perturbation theory approach to estimate the transition temperature of the charge density wave transition of $\mathrm{TiS}{\mathrm{e}}_{2}$. The softening of the phonon mode at the $L$ point where in $\mathrm{TiS}{\mathrm{e}}_{2}$ a giant Kohn anomaly occurs, and the energy difference between the normal and distorted phase are analyzed. Both features are studied as functions of the electronic temperature, which corresponds to the Fermi-Dirac distribution smearing

Raman scattering is a powerful tool for investigating the vibrational properties of two-dimensional materials. Unlike the 2H phase of many transition metal dichalcogenides, the 1T phase of TiSe₂ features a Raman-active shearing and breathing mode, both of which shift toward lower energy with increasing number of layers. By systematically studying the Raman signal of 1T-TiSe₂ in dependence of the sheet thickness, we demonstrate that the charge density wave transition of this

We report long-range ferromagnetic ordering in a vanadium-doped monolayer WSe2 semiconductor using spin-polarized density functional calculations. We found that the vanadium dopant is located in the fully occupied state inside the valence band, inherent from spin–orbit coupling, leading to the presence of free holes in the valence band. As a consequence, the spin-polarized hole carriers are delocalized not only in the vanadium site but also persistently in the tungsten sites distant from vanadiu

Structural phase transitions in layered two-dimensional (2D) materials are of significant interest owing to their ability to exist in multiple metastable states with distinctive properties. However, phase transition in bulk MoS₂ by nondestructive electron infusion has not yet been realized. In this study, we report the 2H to 1T' phase transition and in-between intermediates in bulk MoS₂ using MoS₂/[Ca₂N]⁺·e^- heterostructures, in w

Magnetic order has been proposed to arise from a variety of defects, including vacancies, antisites, and grain boundaries, which are relevant in numerous electronics and spintronics applications. Nevertheless, its magnetism remains controversial due to the lack of structural analysis. The escalation of ferromagnetism in vanadium-doped WSe₂ monolayer is herein demonstrated by tailoring complex configurations of Se vacancies (Se_Vac ) via post heat-treatment. Structural analys

Atomically thin 2D van der Waals semiconductors are promising candidates for next-generation nanoscale field-effect transistors (FETs). Although large-area 2D van der Waals materials have been successfully synthesized, such nanometer-length-scale devices have not been well demonstrated in 2D van der Waals semiconductors. Here, controllable nanometer-scale transistors with a channel length of ≈10 nm are fabricated via vertical channels by squeezing an ultrathin insulating spacer between the out-o

Titanium nitride (Ti 2 N) MXene QDs display efficient deep-UV absorption and light emission.

The mechanism of doping carbon nanotubes (CNTs) with a salt solution was investigated using the density functional theory. We propose that the anion-CNT complex is a key component in doping CNTs. Although the cations play an important role in ionizing CNTs as an intermediate precursor, the ionized CNTs are neutralized further by forming a stable anion-CNT complex as a final reactant. The anion-CNT bond has a strong ionic bonding character and clearly shows p-type behavior by shifting the Fermi l

While valley polarization with strong Zeeman splitting is the most prominent characteristic of two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductors under magnetic fields, enhancement of the Zeeman splitting has been demonstrated by incorporating magnetic dopants into the host materials. Unlike Fe, Mn, and Co, V is a distinctive dopant for ferromagnetic semiconducting properties at room temperature with large Zeeman shifting of band edges. Nevertheless, little known is the ex

One-side chemical conjugation of bilayer graphene has limitations not only on opening a band gap of less than 0.2 eV due to a small electric field across bilayer graphene but also on generating highly degenerate semiconducting properties by shifting the Fermi level into either a valence band or a conduction band due to the requirement of heavy doping concentration. Here, we proposed a new strategy of band-gap engineering of bilayer graphene by chemically conjugating double sides of bilayer graph

Different bulk structures of graphite oxide were systematically investigated using density functional theory (DFT). Our model consisted of a hexagonal in-plane structure of graphene with hydroxyl and epoxide groups, and different oxidation levels and water content. The graphitic AB stacking order was stable in anhydrous graphite oxide, independent of oxidation levels. The hydrogen bonding interaction of layers became weaker as the oxidation level increased to the saturation limit. When water mol