Influence of SiO2 or SiNx passivation on the electrical properties of GaN-based nanorod LEDs

Compared with the conventional plane LEDs, the nanorod LEDs will commonly have poor electrical properties. The dangling bonds at the side wall of nanorods will not only lead to the serious leakage current, but also decrease the hole density in p-GaN layer. It is necessary to passivate the dangling bonds to improve the electrical performance of nanorods LEDs. In this paper, by applying the standard SOG (spin on glass) planarization process, we study the influence of SiO₂ or SiNx passivation layers with different thickness on the electrical properties of GaN-based nanorods LEDs. The experimental results show that SiNx give the better passivation effect on the dangling bonds than that of SiO₂, but induce more hydrogen atom into the p-GaN region of the nanorods which will reduce the hole concentration in p-GaN. The electrical performance of the nanorod LEDs can be greatly improved after appropriate passivation treatment. The optimized passivation layer is 30nm SiNx, which has the lowest operate voltage and a relative low reverse current.