Ultraviolet emissions realized in ZnO via avalanche multiplication process

Au/MgO/ZnO/MgO/Au structures have been designed and constructed in this study. Under a bias voltage, a carrier avalanche multiplication will occur via an impact ionization process in the MgO layer. The generated holes will be drifted into the ZnO layer, and recombine radiatively with the electrons in the ZnO layer, thus obvious emissions at around 387 nm coming from the near-band-edge emission of ZnO will be observed. The results reported in this paper demonstrate the ultraviolet (UV) emission realized via a carrier multiplication process, thus may provide an alternative route to efficient UV emissions by bypassing the challenging p-type doping issues of ZnO.