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Kelvin probe force microscopy (KPFM) has been employed to probe chargecarriers in a graphene/hexagonal boron nitride (hBN) heterostructure [NanoLett, 21, 5013 (2021)]. We propose an approach for operating valley filteringbased on the KPFM-induced potential $U_0$ instead of using external or inducedpseudo-magnetic fields in strained graphene. Employing a tight-binding model,we investigate the parameters and rules leading to valley filtering in thepresence of a graphene quantum dot (GQD) created by the KPFM tip. This modelleads to a resolution of different transport channels in reciprocal space,where the electron transmission probability at each Dirac cone ($K_1$= -K and$K_2$ = +K) is evaluated separately. The results show that U0 and the Fermienergy $E_F$ control (or invert) the valley polarization, if electrons areallowed to flow through a given valley. The resulting valley filtering isallowed only if the signs of $E_F$ and $U_0$ are the same. If they aredifferent, the valley filtering is destroyed and might occur only at someresonant states affected by $U_0$. Additionally, there are independent valleymodes characterizing the conductance oscillations near the vicinity of theresonances, whose strength increases with $U_0$ and are similar to thoseoccurring in resonant tunneling in quantum antidots and to the Fabry-Perotoscillations. Using KPFM, to probe the charge carriers, and graphene-basedstructures to control valley transport, provides an efficient way for attainingvalley filtering without involving external or pseudo-magnetic fields as inprevious proposals.

Valley-dependent tunneling through electrostatically created quantum dots in heterostructures of graphene with hexagonal boron nitride