Study on the electroluminescence properties of diodes based on n-ZnO/p-NiO/p-Si heterojunction

We fabricated the light-emitting diodes (LEDs) consisting of n-ZnO/p-NiO/p-Si heterostructure by using metal-organic chemical vapor deposition (MOCVD) combined with radio frequency (RF) magnetron sputtering. The devices exhibited diode-like rectifying current-voltage characteristics and had a turn-on voltage of 6.8 V. Under forward bias, a prominent broad emission peaked around 400-650 nm was observed at room temperature. The asymmetric electroluminescence (EL) spectra were consisted of two apparent bands, which located at 420 and 495 nm corresponding to the violet and green luminescence, respectively. Furthermore, the mechanism of the light emission was tentatively discussed in terms of the band diagrams of the heterojunction.