  Graphene-based, high quality two-dimensional electronic systems have emerged
as a highly tunable platform for studying superconductivity. Specifically,
superconductivity has been observed in both electron-doped and hole-doped
twisted graphene moire systems, whereas in crystalline graphene systems,
superconductivity has so far only been observed in hole-doped rhombohedral
trilayer and hole-doped Bernal bilayer graphene (BBG). Recently, enhanced
superconductivity has been demonstrated in BBG due to the proximity with a
monolayer WSe2. Here, we report the observation of superconductivity and a
series of flavor-symmetry-breaking phases in both electron- and hole-doped
BBG/WSe2 device by electrostatic doping. The strength of the observed
superconductivity is tunable by applied vertical electric fields. The maximum
Berezinskii-Kosterlitz-Thouless (BKT) transition temperature for the electron-
and hole-doped superconductivity is about 210 mK and 400 mK, respectively.
Superconductivities emerge only when applied electric fields drive BBG electron
or hole wavefunctions toward the WSe2 layer, underscoring the importance of the
WSe2 layer in the observed superconductivity. We find the hole-doped
superconductivity violates the Pauli paramagnetic limit, consistent with an
Ising-like superconductor. In contrast, the electron-doped superconductivity
obeys the Pauli limit, even though the proximity induced Ising spin-orbit
coupling is also notable in the conduction band. Our findings highlight the
rich physics associated with the conduction band in BBG, paving the way for
further studies into the superconducting mechanisms of crystalline graphene and
the development of novel superconductor devices based on BBG.
