Localized surface plasmon enhanced electroluminescence of n-ZnCdO/MgO/p-GaN via Ag nanoparticle decoration

Herein, a n-ZnCdO/MgO dual-layer structure was prepared on p-GaN/c-Al2O3 substrate by pulsed laser deposition method. Then, a layer of Ag nanoparticles, obtained by annealing Ag films with different thicknesses in vacuum, were introduced onto the MgO film to form localized surface plasmon. n-ZnCdO/p-GaN heterojunction diodes were constructed by evaporating Ni/Au electrodes on the p-GaN surface and sintering In pellets on the n-ZnCdO surface. By using 6 nm and 20 nm Ag films, whose extinction spectra match to emission peak of p-GaN and n-ZnCdO respectively, electroluminescence of p-GaN and n-ZnCdO have been observably enhanced. The enhanced emissions are mainly depended on resonant coupling between electron-hole pairs in emission layers and surface plasmon of Ag nanoparticles. These results show that the heterojunction diodes can achieve the enhanced dual-mode emission by adjusting the thickness of the Ag film when the MgO blocking layer is located between n-ZnCdO and p-GaN. This work of realizing multi-color luminescence can provide an experimental method for the design of white light devices.