  Recently V-based Kagome metal attracted intense attention due to the
emergence of superconductivity in the low temperature. Here we report the
fabrication and physical investigations of the high quality single-crystalline
thin films of the Kagome metal KV$_3$Sb$_5$. For the sample with the thickness
of about 15 nm, the temperature dependent resistance reveals a
Berezinskii-Kosterlitz-Thouless (BKT) type behavior, indicating the presence of
two-dimensional superconductivity. Compared with the bulk sample, the onset
transition temperature $T^{onset}_{c}$ and the out-of-plane upper critical
field $H_{c2}$ are enhanced by 15\% and more than 10 times respectively.
Moreover, the zero-resistance state is destroyed by a magnetic field as low as
50 Oe. Meanwhile, the temperature-independent resistance is observed in a wide
field region, which is the hallmark of quantum metallic state. Our results
provide evidences for the existence of unconventional superconductivity in this
material.
