Description:
<jats:p>Plasma-enhanced chemical vapor-deposited SiO2 and SiNx were used to passivate ZnO heterojunction light emitting diodes (LEDs). Postdielectric deposition annealing was critical in obtaining good LED electrical and optical characteristics. No diode characteristics or light emission was observed unless the structures were annealed at 350°C after fabrication. Annealed diodes showed a band-edge electroluminescence (EL) (385nm) and a broad defect band with a peak at 930nm at room temperature. The SiO2 and SiNx had very different passivation effects in terms of the electrical and EL characteristics of the LEDs. After annealing, the SiO2 passivated ZnO LEDs showed diode I-V characteristics and emitted light. However, the annealed SiNx-passivated ZnO LEDs showed leaky diode characteristics and no light emission. We attribute these differences to the role of hydrogen on the LEDs.</jats:p>