Coupling and interface effects in MoS₂/WSe₂ van der Waals nanostructure

Abstract

In this work we report the effects of the interface coupling, the effective mass, the Hartree and exchange–correlation potential on the total energy in quasi-2D MoS2/WSe2 van der Waals nanostructure. Analytical and numerical solutions of the total energy as a function of carrier density and effective mass are determined without self-consistent calculation. The calculation carefully indicates how the quasi-2D electron gas arises from the interface coupling between MoS2 and WSe2 layers. Moreover, the results showed that the width of the wave function and the length scale between the two materials’ interface decrease with increasing electron density while the corresponding ground state quantisation energy in the z-direction increases considerably. Furthermore, in MoS2 layer with density n s = 4 × 1012 cm−2 this additional separation is approximately 2 nm and 〈z〉 = 1 nm. Due to the disparity in effective mass of electrons and holes in MoS2, the majority of the excess energy is absorbed as kinetic energy by electrons. The comparison with available experimental and DFT calculation indicates that the present work reproduces properly known results for MoS2/WSe2 interface.

The optical gain variation of Ge nanowires induced by L-valley splitting under the [110] direction stress

“…In view of the fact that the effective-mass theory has been successfully used to describe the electronic structures of lowdimensional nanostructures, [19][20][21][22] especially nanowires or quantum wires, the band structures of Ge nanowires at the Γ-valley and L-valley under the [110] direction uniaxial stress are investigated firstly using the k•p theory in this paper, and the calculated results show that the eight degenerate L-valleys of Ge nanowires will be split into two group of L 1 -valleys and L 2 -valleys with fourfold degeneracy. Interestingly, the electron energy levels at the L 1 -valleys and L 2 -valleys will approach and go away from those at the Γ-valley, respectively, with increasing stress.…”