  In the nitrogen-doped lutetium hydride (Lu-H-N) system, the presence of Lu-N
chemical bonds plays a key role in the emergence of possible room-temperature
superconductivity at near ambient pressure. However, due to the synthesis of
single-crystalline LuN being a big challenge, the understanding of LuN is
insufficient thus far. Here, we report on the epitaxial growth of
single-crystalline LuN films. The crystal structures of LuN films were
characterized by high-resolution X-ray diffraction. The measurement of
low-temperature electrical transport indicates the LuN film is semiconducting
from 300 to 2 K, yielding an activation gap of $\sim$ 0.02 eV. Interestingly,
negative magnetoresistances can be observed below 12 K, which can result from
the defects and magnetic impurities in LuN films. Our results uncover the
electronic and magnetic properties of single-crystalline LuN films.
