Éxcitons inter-camada em heteroestruturas de Van der Waals na presença de um campo elétrico perpendicular

Abstract

Excitons are quasi-particles formed by an bound electron-hole pair that appear in semiconductors when an electron in the valence band is excited to the conduction band. In this work, we study the binding energy of interlayer excitons (which occur when the e-h pair is located in differentlayers in real space) which appear in two dimensional semiconducting heterostructures. We investigate three different systems to probe the exciton binding energy as a function of an external perpendicular electric field. First, we analyse a heterobilayer consisting of MoS2/WSe2, and heterotrilayers consisting of MoS2/WSe2/MoS2 and WSe2/MoS2/WSe2. In our model, the heterostructures are encapsulated by hexagonal boron nitride and the medium between the layers is vacuum. Due the dielectric screening, the interaction potential between the electron-hole pair is no longer Coulombian. In order to find this potential we solve the Poisson equation in a medium with N interfaces. We use the effective mass and the tight-binding models to construct the exciton Hamiltonian in each system. Finally, we study the behavior of the exciton wave function, focusing on their degree of overlap.