Room-temperature operation at 333 nm of Al0.03Ga0.97N/Al0.25Ga0.75N quantum-well light-emitting diodes with Mg-doped superlattice layers

Abstract

We demonstrate room-temperature deep ultraviolet (UV) current injection emission from ${\mathrm{Al}}_{\mathrm{0.03}}{\mathrm{Ga}}_{\mathrm{0.97}}{\mathrm{N/Al}}_{\mathrm{0.25}}{\mathrm{Ga}}_{\mathrm{0.75}}\mathrm{N}$ multiquantum-well (MQW) light-emitting diodes (LEDs) fabricated by metalorganic vapor phase epitaxy. The electroluminescence (EL) peaked at 333.0 nm under pulsed current injection. To our knowledge, this is the shortest wavelength ever reported for nitride QW LEDs. A Mg-doped GaN/AlGaN superlattice (SL) hole conductive layer was used as a p-type layer in order to enable current injection into such deep-level AlGaN QWs. We observed single-peak near band-edge emission from the QWs. The output intensity did not saturate up to current densities of 0.33 kA/cm². We obtained a reasonable well width dependence on the EL peak wavelength of ${\mathrm{Al}}_{\mathrm{0.01}}{\mathrm{Ga}}_{\mathrm{0.99}}\mathrm{N}$ MQW LEDs, which confirms that the main emission peak originates from the QW regions. These results revealed that the Mg-doped SL hole conductive layers are highly suitable for application to GaN-based UV light-emitting devices.