  We use ionic liquid-assisted electric field effect to tune the carrier
density in an electron-doped cuprate ultrathin film and cause a two-dimensional
superconductor-insulator transition (SIT). The low upper critical field in this
system allows us to perform magnetic field (B)-induced SIT in the liquid-gated
superconducting film. Finite-size scaling analysis indicates that SITs induced
both by electric and magnetic field are quantum phase transitions and the
transitions are governed by percolation effects - quantum mechanical in the
former and classical in the latter case. Compared to the hole-doped cuprates,
the SITs in electron-doped system occur at critical sheet resistances (Rc) much
lower than the pair quantum resistance RQ=h/(2e)2=6.45 k{\Omega}, suggesting
the possible existence of fermionic excitations at finite temperature at the
insulating phase near SITs.
