Room temperature electroluminescence from the n-ZnO/p-GaN heterojunction device grown by MOCVD

The heterojunction light-emitting diode with n-ZnO/p-GaN structure was grown on (0 0 0 1) sapphire substrate by metalorganic chemical vapor deposition (MOCVD) technique. The heterojunction structure was consisted of an Mg-doped p-type GaN layer with a hole concentration of ∼1017 cm−3 and a unintentionally doped n-type ZnO layer with an electron concentration of ∼1018 cm−3. A distinct blue-violet electroluminescence with a dominant emission peak centered at ∼415 nm was observed at room temperature from the heterojunction structure under forward bias conditions. The origins of the electroluminescence (EL) emissions are discussed in comparison with the photoluminescence spectra, and it was supposed to be attributed to a radiative recombination in both n-ZnO and p-GaN sides.