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DOE OSTI · 1783789

Localized Excitons in NbSe 2 -MoSe 2 Heterostructures

Joshi, Jaydeep·Zhou, Tong·Krylyuk, Sergiy·Davydov, Albert V.·Žutić, Igor·Vora, Patrick M.
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Abstract

Neutral and charged excitons (trions) in atomically thin materials offer important capabilities for photonics, from ultrafast photodetectors to highly efficient light-emitting diodes and lasers. Recent studies of van der Waals (vdW) heterostructures comprised of dissimilar monolayer materials have uncovered a wealth of optical phenomena that are predominantly governed by interlayer interactions. Here, we examine the optical properties in NbSe 2 -MoSe 2 vdW hetero- structures, which provide an important model system to study metal–semiconductor interfaces, a common element in optoelectronics. Through low-temperature photoluminescence (PL) microscopy, we discover a sharp emission feature, L1, that is localized at the NbSe 2 -capped regions of MoSe 2 . L1 is observed at energies below the commonly studied MoSe 2 excitons and trions and exhibits temperature- and power-dependent PL consistent with exciton localization in a confining potential. This PL feature is robust, observed in a variety of samples fabricated with different stacking geometries and cleaning procedures. Using first-principles calculations, we reveal that the confinement potential required for exciton localization naturally arises from the in-plane band bending due to the changes in the electron affinity between pristine MoSe 2 and NbSe 2 -MoSe 2 heterostructure. Here, we discuss the implications of our studies for atomically thin optoelectronics devices with atomically sharp interfaces and tunable electronic structures.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRYdensity functional theoryexcitonsphotoluminescencetransition metal dichalcogenidesvan der Waals heterostructures

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Joshi, Jaydeep, Zhou, Tong, Krylyuk, Sergiy, Davydov, Albert V., Žutić, Igor, Vora, Patrick M.. 2020-07-08. Localized Excitons in NbSe 2 -MoSe 2 Heterostructures. https://doi.org/10.1021/acsnano.0c02803

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