  We have studied electronic conductivity and shot noise of bilayer graphene
(BLG) sheets at high bias voltages and low bath temperature $T_0=4.2$ K. As a
function of bias, we find initially an increase of the differential
conductivity, which we attribute to self-heating. At higher bias, the
conductivity saturates and even decreases due to backscattering from optical
phonons. The electron-phonon interactions are also responsible for the decay of
the Fano factor at bias voltages $V>0.1$ V. The high bias electronic
temperature has been calculated from shot noise measurements, and it goes up to
$\sim1200$ K at $V=0.75$ V. Using the theoretical temperature dependence of BLG
conductivity, we extract an effective electron-optical phonon scattering time
$\tau_{e-op}$. In a 230 nm long BLG sample of mobility $\mu=3600$
cm$^2$V$^{-1}$s$^{-1}$, we find that $\tau_{e-op}$ decreases with increasing
voltage and is close to the charged impurity scattering time $\tau_{imp}=60$ fs
at $V=0.6$ V.

Mesoscale and Nanoscale Physics;Materials Science