heterostructures*

Excitons with large binding energy are formed in atomically thin semiconductors because of the insufficient dielectric screening outside of the 2D layers. In a vertical heterostructure consisting of MoSe₂ and WSe₂ monolayers, the type-II band alignment leads to the rapid transfer of electron to the MoSe₂ layer and hole to the WSe₂ layer, forming interlayer excitons with drastically different properties than excitons confined within one monolayer. We investigate the interlayer exciton diffusion in MoSe₂/WSe₂ heterostructures. We compare a mechanically stacked heterostructure with hexagonal boron nitride (hBN) encapsulation and one grown by chemical vapor deposition (CVD). Spatially and time-resolved photoluminescence measurements are performed at low-temperature. Interlayer exciton diffusion length and coefficient are extracted in both heterostructures and found to be rather different.