  We performed systematic angle-resolved photoemission spectroscopy
measurements $in$-$situ$ on $T'$-${\rm La}_{2-x}{\rm Ce}_x\rm
{CuO}_{4\pm\delta}$ (LCCO) thin films over the extended doping range prepared
by the refined ozone/vacuum annealing method. Electron doping level ($n$),
estimated from the measured Fermi surface volume, varies from 0.05 to 0.23,
which covers the whole superconducting dome. We observed an absence of the
insulating behavior around $n \sim$ 0.05 and the Fermi surface reconstruction
shifted to $n \sim$ 0.11 in LCCO compared to that of other electron-doped
cuprates at around 0.15, suggesting that antiferromagnetism is strongly
suppressed in this material. The possible explanation may lie in the enhanced
-$t'$ /$t$ in LCCO for the largest $\rm{La^{3+}}$ ionic radius among all the
Lanthanide elements.
