Enhancement of the near-band-edge electroluminescence from the active ZnO layer in the ZnO/GaN-based light emitting diodes using AlN-ZnO/ZnO/AlN-ZnO double heterojunction structure

In this work, an AlN-ZnO/ZnO/AlN-ZnO double heterojunction (DH) structure prepared using the cosputtering technology was deposited onto the p-type GaN epitaxial layer. The indiffusion of the oxygen atoms to the p-GaN epilayer was obstructed as the cosputtered AlN-ZnO film inset between n-ZnO/p-GaN interface. The near-ultraviolet (UV) emission from this ZnO/GaN-based light emitting diode (LED) was greatly improved as compared to an n-type ZnO film directly deposited onto the p-GaN epilayer. Meanwhile, the native defects in the n-ZnO layer associated with the green luminescence was less likely to form while it was sandwiched by the cosputtered AlN-ZnO film. As the thickness of the active n-ZnO layer in the DH structure reached 10 nm, the near-band-edge (NBE) emission became the predominated luminescence over the resulting LED spectrum.