Localized Excitons in NbSe2-MoSe2 Heterostructures
Jaydeep Joshi, Tong Zhou, Sergiy Krylyuk, Albert Davydov, Igor Zutic, Patrick M. Vora
Neutral and charged excitons (trions) in atomically-thin materials offer important capabilities for photonics, from ultrafast photodetectors to highly-efficient lightemitting 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 NbSe2 - MoSe2 vdW heterostructures, 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 NbSe2-capped regions of MoSe2. L1 is observed at energies below the commonly-studied MoSe2 excitons and trions, and exhibits temperature- and power-dependent PL consistent with exciton localization in a confining potential. Remarkably, L1 is very robust not just in different samples, but also under very different processing conditions. Using firstprinciples calculations we reveal that the confinement potential required for exciton localization naturally arises from the in-plane band bending due to the changes of the electron affinity in the NbSe2 - MoSe2 heterostructures. We discuss the implications of our studies for atomically-thin optoelectronics devices with atomically-sharp interfaces and tunable electronic structures.
, Zhou, T.
, Krylyuk, S.
, Davydov, A.
, Zutic, I.
and Vora, P.
Localized Excitons in NbSe2-MoSe2 Heterostructures, ACS Nano, [online], https://doi.org/10.1021/acsnano.0c02803
(Accessed April 19, 2021)