Asymmetric valley polarization and photoluminescence in MoS/MoO heterostructure.

We investigate circularly polarized photoluminescence (PL) in the MoS/MoO heterostructure, which was fabricated by transferring MoS monolayer to cover the MoO few layers on the SiO/Si substrate. It is shown that the PL with the same helicity as the excitation light is dominant due to the inherent chiral optical selectivity, which allows exciting one of the valleys in MoS monolayer. The degree of polarization (DP), which characterizes the intensity difference of two chiral components of PL, is unequal for the right-handed and left-handed circularly polarized excitations in the MoS/MoO heterostructure.