The surface plasmon (SP) resonance was used to increase the emission efficiencies toward high efficiency light-emitting diodes (LEDs). We obtained the enhancements of the electroluminescence from the fabricated plasmonic LED device structure by employing the very thin p+-GaN layer. The further enhancements should be achievable by optimization of the metal and device structures. Next important challenge is to extend this method from the visible to the deep UV region. By using Aluminum, we obtained the enhancements of emissions at ∼260 nm from AlGaN/AlN quantum wells. We succeeded to control the SP resonance by using the various metal nanostructures. These localized SP resonance spectra in the deep-UV regions presented here would be useful to enhance deep UV emissions of super wide bandgap materials such as AlGaN/AlN. We believe that our approaches based on ultra-deep UV plasmonics would bring high efficiency ultra-deep UV light sources.