Study on the luminescence properties of n-ZnO/i-NiO/n-GaN isotype heterojunction diodes

The n-ZnO/i-NiO/n-GaN isotype heterojunction diode was fabricated by metal organic chemical vapor deposition (MOCVD) on the n-GaN/sapphire substrate. The current–voltage (I–V) measurement showed typical rectification characteristics with a turn-on voltage of 2.5 V. An ultraviolet emission peak around 363 nm was observed from the EL spectra at room temperature. High ultraviolet light extraction efficiency was proved by a superlinear curve of the intensity ratio of ultraviolet to visible emission. The mechanism of electroluminescence has been tentatively elucidated in terms of band diagrams of the heterojunction. - Highlights: ► The n-ZnO/i-NiO/n-GaN isotype heterojunction diode was fabricated by MOCVD. ► NiO could be used as the effective electron blocking layer for n-ZnO/n-GaN heterojunction. ► The dielectric NiO layer could enhance the UV emission efficiency of the LED greatly.