Angle-dependent transmission in graphene heterojunctions

We describe an experimental setup for measuring angle-dependent transmission due to Klein tunneling through quasi-ballistic graphene heterojunctions. Our devices consist of straight and angled leads, in which the barrier height is controlled by a shared gate electrode. Using a balancing technique and a differential measurement, we show how to isolate the angle-dependent contribution to the resistance from other angle-insensitive, gate-dependent, and device-dependent effects. We find that our baseline signal is dominated by mesoscopic conductance fluctuations, but that the increase in the fluctuation amplitude is due to angle-dependent transmission. (C) 2015 AIP Publishing LLC.