Observation of Interlayer Excitons in Monolayer MoSe2-WSe2 Heterostructure on BN Substrate*

Interlayer excitons have previously been observed in monolayer MX2 heterostructures exhibiting type II band alignment. Specically, interlayer excitons in MoSe2-WSe2 heterostructures have been thoroughly characterized with photoluminescence (PL) and photoluminescence excitation spectroscopy (PLE). However, electrical control of the interlayer exciton exhibits PL intensity dependence that is inconsistent with the dipole and electric field model - possibly owing to carrier charge effects - and requires further elucidation. The addition of BN substrate, which has been shown to (1) smooth the surface and (2) reduce carrier charge inhomogeneity of graphene devices, presents itself as a potential solution. In this preliminary study, we fabricated an MoSe2-WSe2 heterostructure on BN substrate. Photoluminescence (PL) measurements on the device confirm the presence of interlayer excitons at approximately 1.40 eV, consistent with MoSe2-WSe2 heterostructures. Furthermore, the PL characterization reveals unreported spectral features for both the interlayer and intralayer excitons.