Tunable Electronic and Dielectric Properties of Molybdenum Disulfide

Abstract

We report tunability in electronic and dielectric properties of a technologically promising nanomaterial MoS 2 . The properties of MoS 2 can be tuned by varying the layer thickness, by applying mechanic strain, by tuning the interlayer distance, and by applying external electric field. Reducing the slab thickness systematically from bulk to monolayers causes blue shift in the band gap energies, thereby, resulting in tunability of the electronic band gap. By reducing the number of layers from bulk to monolayer limit, electron energy loss spectra (EELS) shows red shift in the energies of both p and p þ r plasmons. Mechanical strains reduce the band gap of monolayer MoS 2 by causing a direct-to-indirect band gap transitions and finally rendering it into metal at critical values depending on the types of applied strain. Dielectric properties of monolayer MoS 2 too get influenced by the type of applied strain. Imaginary part of dielectric function (e 2 ) shows redshift in the structure peak energy on the application of strains with significant dependence on the types of applied strain. In-plane strains also cause semiconductormetal transitions (e T ) in bilayer sheets of MoS 2 . The energy gap of semiconducting bilayer MoS 2 gets reduced continuously by reducing the bilayer separation, eventually rendering it metallic at critical value of interlayer distance. Electrically gated semiconducting bilayer MoS 2 is also found to show reduction in the band gap on increasing the magnitude of electric field and results in band gap closure at a critical value of the field.

Tuning the electronic properties of bondings in monolayer MoS2 through (Au, O) co-doping

“…It can be found that the band structures adjacent to the band gap of un-doped monolayer MoS 2 calculated by GGA and GGA+U methods are mainly dominated by the hybridization of Mo 4d and S 3p orbitals, which is consistent with previous calculated results [17][18]. The Brillouin-zone of the monolayer MoS 2 was performed over the 7×7×1 k-point grids using the Monkorst-Pack method, where the self-consistent convergence of the total energy is 1.0×10 -5 eV/atom.…”

Recent Advances in Strain-Induced Piezoelectric and Piezoresistive Effect-Engineered 2D Semiconductors for Adaptive Electronics and Optoelectronics

“…The large piezoresistive effects in semiconductors demanded a fundamental theory of the physics. Strain in a crystalline solid modifies the lattice constants and reduces the crystal symmetry, leading to significant shifts in the (2.5) = E energy band edges [62]. The existing theories were based on the change in energy band structure (including band warping and splitting) [63].…”

Ultrafast exciton relaxation in monolayer transition metal dichalcogenides

“…The study of exciton based quantum dynamical processes is important as excitonic interactions underlie the unique optoelectronic properties 5,[15][16][17][18] of monolayer dichalcogenides. Several applications [19][20][21][22][23][24] can be linked to the rich many-body effects of excitons in low-dimensional transition metal dichalcogenides.…”