In this work, a 280-nm-wavelength deep-ultraviolet light-emitting diode (DUV LED) with a p+-GaN/SiO2/ITO tunnel junction is fabricated and investigated. Due to the decreased tunnel region width and enhanced electric field intensity in the 1-nm-thick SiO2 layer, the interband tunneling efficiency and the corresponding hole injection efficiency are promoted. Therefore, the external quantum efficiency (EQE) for the proposed device is increased when compared with a traditional DUV LED. In addition, an improved current spreading effect is observed for our proposed device. As a result, improved wall-plug efficiency (WPE) is obtained owing to the increased optical power and decreased forward operating voltage. Meanwhile, the enhanced electric field intensity in the SiO2 layer reduces the voltage drop in the p-n junction region for the proposed device, and thus the leakage current is reduced.