Blue/green electroluminescence from a ZnO nanorods/p-GaN heterojunction light emitting diode under different reverse bias

•Blue/green electroluminescence from a ZnO nanorods/p-GaN heterojunction LED operated at different reverse bias was demonstrated.•The color of the device could be turned from green to blue by varying the reverse bias voltages.•The electroluminescence mechanism of the heterojunction LED was revealed in terms of interface defects and band diagram.