  Single charge control of localized excitons (LXs) in two-dimensional
transition metal dichalcogenides (TMDCs) is crucial for potential applications
in quantum information processing and storage. However, traditional
electrostatic doping method with applying metallic gates onto TMDCs may cause
the inhomogeneous charge distribution, optical quench, and energy loss. Here,
by locally controlling the ferroelectric polarization of the ferroelectric thin
film BiFeO3 (BFO) with a scanning probe, we can deterministically manipulate
the doping type of monolayer WSe2 to achieve the p-type and n-type doping. This
nonvolatile approach can maintain the doping type and hold the localized
excitonic charges for a long time without applied voltage. Our work
demonstrated that ferroelectric polarization of BFO can control the charges of
LXs effectively. Neutral and charged LXs have been observed in different
ferroelectric polarization regions, confirmed by magnetic optical measurement.
Highly circular polarization degree about 90 % of the photon emission from
these quantum emitters have been achieved in high magnetic fields. Controlling
single charge of LXs in a non-volatile way shows a great potential for
deterministic photon emission with desired charge states for photonic long-term
memory.
