Electroluminescence from ZnO nanowires in n-ZnO film/ZnO nanowire array/ p-GaN film heterojunction light-emitting diodes

ZnO nanowire-array-embedded n-ZnOp-GaN heterojunction light-emitting diodes were fabricated by growing Mg-doped p-GaN films, ZnO nanowire arrays, and polycrystalline n-ZnO films consecutively. Electroluminescence emission having the wavelength of 386 nm was observed under forward bias in the heterojunction diodes and the UV-violet light was emerged from the ZnO nanowires. The heterojunction diode was thermal treated in hydrogen ambient to increase the electron injection rate from the n-ZnO films into the ZnO nanowires. High concentration of electrons supplied from the n-ZnO films activated the radiative recombination in the ZnO nanowires, i.e., increased the light-emitting efficiency of the heterojunction diode.