arXiv subjects

Mohammad Bahmani

Publications and source records attributed to Mohammad Bahmani.

3 recordsLinked to original sources

arXiv2021

Reversible tuning the optical properties of defective TMDs monolayers

Potential applications of monolayer of transition metal dichalcogenides (TMDs) in optoelectronic and flexible devices are under heavy investigation. Although TMDs monolayers are highly robust to external mechanical fields, their electronic structure is sensitive to compressive and tensile strain. Besides, intrinsic point defects are present in synthesized samples of these two dimensional (2D) materials which leads to the modification of their electronic and optical properties. Presence of vacancy complexes leads to absorption with larger dipole matrix elements in comparison to the case of simple transition metal vacancies. Using first principles calculations, we scrutinize the effect of various strain situations on the absorption spectra of such defective monolayers and show that strain engineering allows for reversible tuning of the optical properties.

physics.comp-ph↗

arXiv2021

Effect of Interfacial Defects on the Electronic Properties of MoS$_2$ Based Lateral T-H Heterophase Junctions

The coexistence of semiconducting (2H) and metallic (1T) phases of MoS$_{2}$ monolayers have further pushed their strong potential for applications in the next generation of electronic devices based on the two-dimensional lateral heterojunctions. Structural defects have considerable effects on the properties of these 2D devices. In particular, the interfaces of two phases are often imperfect and may contain numerous vacancies created by phase engineering techniques, e.g. under the electron beam. Here, the transport behaviors of the heterojunctions in the existence of point defects are explored by means of first-principles calculations and non-equilibrium Green's function approach. While vacancies in semiconducting MoS$_{2}$ act as scattering centers, their presence at the interface improves the flow of the charge carriers. In the case of $V_{Mo}$, the current has been increased by two orders of magnitude in comparison to the perfect device. The enhancement of transmission was explained by changes in the electronic densities at the T-H interface, which open new transport channels for electron conduction.

physics.comp-ph↗

arXiv2019

Electronic Properties of Defective MoS$_{2}$ Monolayers Subject to Mechanical Deformations: A First-Principles Approach

Monolayers (ML) of Group-6 transition-metal dichalcogenides (TMDs) are semiconducting two-dimensional materials with direct bandgap, showing promising applications in various fields of science and technology, such as nanoelectronics and optoelectronics. These monolayers can undergo strong elastic deformations, up to about 10\%, without any bond breaking. Moreover, the electronic structure and transport properties, which define the performance of these TMDs monolayers in nanoelectronic devices, can be strongly affected by the presence of point defects, which are often present in the synthetic samples. Thus, it is important to understand both effects on the electronic properties of such monolayers. In this work, we have investigated the electronic structure and energetic properties of defective MoS$_{2}$ monolayers, as subject to various strains, using density functional theory simulations. Our results indicated that strain leads to strong modifications of the defect levels inside the bandgap and their orbital characteristics. Strain also splits the degenerate defect levels up to an amount of 450~meV, proposing novel applications.

physics.comp-ph↗