Improvement in electroluminescence performance of n-ZnO/Ga₂O₃/p-GaN heterojunction light-emitting diodes

n-ZnO/p-GaN heterojunction light-emitting diodes with and without a Ga₂O₃ interlayer are fabricated. The electroluminescence (EL) spectrum of the n-ZnO/p-GaN displays a single blue emission at 430 nm originating from GaN, while the n-ZnO/Ga₂O₃/p-GaN exhibits a broad emission peak from ultraviolet to visible. The broadened EL spectra of n-ZnO/Ga₂O₃/p-GaN are probably ascribed to the radiative recombination in both the p-GaN and n-ZnO, due to the larger electron barrier (ΔE_C=1.85 eV) at n-ZnO/Ga₂O₃ interface and the much smaller hole barrier (ΔE_V=0.20 eV) at Ga₂O₃/p-GaN interface.