Probing Klein tunneling through angle dependence of resistance across graphene p-n junctions

We have studied the angle-dependent resistance characteristics of ``Y''-shaped dual-gated graphene p-n junction devices. Different arms of each device share a common top gate, and the branching of current in the arms at different angles is determined by the transparency of p-n junctions formed under the top gate. For a particular back gate and top gate voltage, we first balanced the voltage drop in the straight and angled arms, and then we studied the variation of the resistance as a function of top gate keeping the back gate voltage fixed. Deviation from the balanced condition with varying top gate voltage measures the transparency of the p-n junctions in the arms. We found that this deviation is large for a p-n*-p or n-p*-n configurations, as compared to p-p*-p or n-n*-n junctions, which provides a direct evidence of the angle-selective transmission of charge carriers in graphene p-n junction.