  Conduction between graphene layers is suppressed by momentum conservation
whenever the layer stacking has a rotation. Here we show that phonon scattering
plays a crucial role in facilitating interlayer conduction. The resulting
dependence on orientation is radically different than previously expected, and
far more favorable for device applications. At low temperatures, we predict
diode-like current-voltage characteristics due to a phonon bottleneck. Simple
scaling relationships give a good description of the conductance as a function
of temperature, doping, rotation angle, and bias voltage, reflecting the
dominant role of the interlayer beating phonon mode.
