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The optical spectra of vertically stacked MoSe$_2$/WSe$_2$ heterostructures contain additional interlayer excitonic peaks that are absent in the individual monolayer materials and exhibit a significant spatial charge separation in out-of-plane direction. Extending on a previous study, we used a many-body perturbation theory approach to simulate and analyse the excitonic spectra of MoSe$_2$/WSe$_2$ heterobilayers with three stacking orders, considering both momentum-direct and momentum-indirect excitons. We find that the small oscillator strengths and corresponding optical responses of the interlayer excitons are significantly stacking-dependent and give rise to high radiative lifetimes in the range of 5-200,ns (at T=4,K) for the bright interlayer excitons. Solving the finite-momentum Bethe-Salpeter Equation, we predict that the lowest-energy excitation should be an indirect exciton over the fundamental indirect band gap (K$rightarrow$Q), with a binding energy of 220,meV. However, in agreement with recent magneto-optics experiments and previous theoretical studies, our simulations of the effective excitonic Lande g-factors suggest that the low-energy momentum-indirect excitons are not experimentally observed for MoSe$_2$/WSe$_2$ heterostructures. We further reveal the existence of interlayer C excitons with significant exciton binding energies and optical oscillator strengths, which are analogous to the prominent band nesting excitons in mono- and few-layer transition-metal dichalcogenides.
The availability of accessible fabrication methods based on deterministic transfer of atomically thin crystals has been essential for the rapid expansion of research into van der Waals heterostructures. An inherent issue of these techniques is the de
Identifying quantum numbers to label elementary excitations is essential for the correct description of light-matter interaction in solids. In monolayer semiconducting transition metal dichalcogenides (TMDs) such as MoSe$_2$ or WSe$_2$, most optoelec
The creation of moire patterns in crystalline solids is a powerful approach to manipulate their electronic properties, which are fundamentally influenced by periodic potential landscapes. In 2D materials, a moire pattern with a superlattice potential
Based on emph{ab initio} theoretical calculations of the optical spectra of vertical heterostructures of MoSe$_2$ (or MoS$_2$) and WSe$_2$ sheets, we reveal two spin-orbit-split Rydberg series of excitonic states below the textsl{A} excitons of MoSe$
We investigate WSe$_2$-MoSe$_2$ heterobilayers with different twist angles $theta pm delta$ between the two layers, by low-frequency Raman scattering. In sufficiently aligned samples with $theta=0^circ$, or $theta=60^circ$, and $delta lesssim 3^circ$