Effect of a p-type ZnO insertion layer on the external quantum efficiency of GaInN light-emitting diodes

摘要： The external quantum ef?ciency (EQE) of a GaInN green light-emitting diode (LED) is improved by inserting a p-type ZnO layer between the indium tin oxide electrode and the p-type GaN layer. Several hypotheses are discussed to explain the EQE improvement in the LED with the ZnO layer. It is concluded that higher hole injection ef?ciency and better electron con?nement explain the EQE improvement, which is supported by the results of device simulations showing that the EQE is sensitive to the polarization sheet charge density at the interface between the last quantum barrier and electron-blocking layer.