  Bulk crystals of electron-doped cuprates with the T'-type structure require
both Ce substitutions and reduction annealing for the emergence of
superconductivity while the reduction annealing alone can induce
superconductivity in thin films of the T'-type cuprates. In order to reveal
low-energy electronic states which are responsible for the superconductivity,
we have conducted angle-resolved photoemission spectroscopy measurements on
thin films of the superconducting Ce-free T'-type cuprate Pr$_2$CuO$_4$. The
results indicate that the overall band structure and the Fermi surface area of
the superconducting Pr$_2$CuO$_4$ are similar to those of superconducting
Ce-doped bulk single crystals, highlighting the importance of the actual
electron concentration rather than the Ce concentration when discussing the
physical properties of the T'-type cuprates.

Superconductivity;Strongly Correlated Electrons