▎ 摘 要
Graphene, a special two-dimensional material, has a unique band structure that allows the type andconcentration of carriers to be controlled through a gate voltage, and it has potential applications in bipolarnanoelectronic devices. In this paper, based on the tight-binding model of graphene p-n junctions, by using thenonequilibrium Green's function method and Landauer-Buttiker formula, the thermal dissipation of electrictransport in graphene p-n junctions in a magnetic field is investigated. Under a strong magnetic field, both sidesof the junction are in the quantum Hall regime, thus the topologically protected chiral edge states appear.Intuitively, the topologically protected chiral edge states are dissipationless. However, the results show thatthermal dissipation can occur in the quantum Hall regime in graphene junctions in the presence of dissipationsources, although the topologically protected chiral edge states still exist. In clean graphene junctions, thermaldissipation occurs mainly at the edge for the unipolar transport, but it occurs both at the edge and at theinterface of the junctions for the bipolar transport. In the presence of disorder, thermal dissipation issignificantly enhanced both in the unipolar junction and in the bipolar junction, and it increases with disorderstrength increasing. Besides, the energy distribution of electrons at different positions is also studied, whichshows that the thermal dissipation always occurs as long as the energy distribution is in nonequilibrium. Thisindicates that the topology can protect only the propagation direction of electrons, but it can not suppress the occurrence of thermal dissipation