Figure 6

Schematic diagrams of the carrier transport, capture, and recombination processes in GaN/GaN MQW LEDs (a) without a graphene electrode, (b) with a graphene electrode, and (c) with a graphene electrode of better film quality. In the diagram (a), without a graphene electrode, a low hole injection efficiency into the MQWs lead to a limited current flow and low electron-hole recombination efficiency. The diagram (b) shows that the graphene electrode will enhance the hole injection efficiency into the MQWs and thus increase electron-hole recombination efficiency. In the diagram (c), as more carriers transport in a larger luminescence area, they will be more efficiently captured into the quantum wells and thus enhance electron-hole recombination.