Interlayer excitons in transition metal dichalcogenide heterostructures

Abstract

Starting from the single-particle Dirac Hamiltonian for charge carriers in monolayer transition metal dichalcogenides (TMDs), we construct a four-band Hamiltonian describing interlayer excitons consisting of an electron in one TMD layer and a hole in the other TMD layer. An expression for the electron-hole interaction potential is derived, taking into account the effect of the dielectric environment above, below, and between the two TMD layers as well as polarization effects in the transition metal layer and in the chalcogen layers of the TMD layers. We calculate the interlayer exciton binding energy and average in-plane interparticle distance for different TMD heterostructures. The effect of different dielectric environments on the exciton binding energy is investigated and a remarkable dependence on the dielectric constant of the barrier between the two layers is found, resulting from competing effects as a function of the in-plane and out-of-plane dielectric constants of the barrier. The polarization effects in the chalcogen layers, which in general reduce the exciton binding energy, can lead to an increase in binding energy in the presence of strong substrate effects by screening the substrate. The excitonic absorbance spectrum is calculated and we show that the interlayer exciton peak depends linearly on a perpendicular electric field, which agrees with recent experimental results. arXiv:1809.01065v1 [cond-mat.mes-hall]

Spectrum of exciton states in monolayer transition metal dichalcogenides: Angular momentum and Landau levels

“…In Table I we give the binding energy of different exciton states in different TMDs, for which we used the parameters given in Table III of Ref. [33]. The results show that, for all exciton states, the binding energy is largest in MoS 2 and smallest in WSe 2 .…”

Electronic and Optoelectronic Applications Based on ReS2

“…However, researchers are getting more interested in anisotropic 2D materials in recent years. One such material is titanium trisulfide (TiS 3 ) which shows strong anisotropic properties and contains metallic chains within each layer . Rhenium disulfide (ReS 2 ), a fresh member of group VII‐TMDs, is also an anisotropic 2D material but with little exploration.…”

“…One such material is titanium trisulfide (TiS 3 ) which shows strong anisotropic properties and contains metallic chains within each layer. [12,13] Rhenium disulfide (ReS 2 ), a fresh member of group VII-TMDs, is also an anisotropic 2D material but with little exploration. ReS 2 has distinct physicochemical properties owing to its unique 1T distorted structure [14] and weak interlayer coupling.…”

Exchange intervalley scattering and magnetic phase diagram of transition metal dichalcogenide monolayers

“…Effects of electron-electron interactions in TMDs were considered previously in Refs. [17][18][19] The results predicted in Refs. 17,18 are valid if the exchange inter-valley (EIV) interaction is negligible.…”