Ultralow Emission Threshold Light-Emitting Diode of Nanocrystalline ZnO/p-GaN Heterojunction

Under an ultralow driven current density about 15mA/cm², a blue electroluminescence could be observed from the nanocrystalline n-ZnO/p-GaN heterojunction light-emitting diode. The photoluminescence spectrum showed a dominant sharp near-band-edge emission, and the deep-level emission of the nanocrystalline ZnO films was not observed. Current–voltage characteristics of the heterojunctions indicated a diodelike rectification behavior. With the increase in the injection current, an ultraviolet emission was observed due to the recombination in ZnO.