Ultraviolet Electroluminescence from MgZnO-Based Heterojunction Light-Emitting Diodes

We report on the fabrication of an n-Mg0.12Zn0.88O/p-GaN heterojunction light-emitting diode with an MgO dielectric interlayer by plasma-assisted molecular beam epitaxy. The current−voltage curve of the heterojunction diode showed obvious rectifying characteristics with a threshold voltage of about 8 V. Under forward bias, an ultraviolet electroluminescence (EL) emission located at about 374 nm coming from the Mg0.12Zn0.88O layer was observed at room temperature. This is one of the shortest EL emissions observed in ZnO-based pn junctions to the best of our knowledge. The origin of the EL emission was elucidated in terms of the carrier transportation process modulated by the MgO interlayer in the heterojunction.