Improvement in Electrical and Optical Performances of GaN-Based LED With SiO₂/Al₂O₃ Double Dielectric Stack Layer

ASiO₂/Al₂O₃double dielectric stack layer was deposited on the surface of a GaN-based light-emitting diode (LED). The double dielectric stack layer increases the optical output power of the LED because the firstAl₂O₃layer plays a role as an effective surface passivation layer and the secondSiO₂layer with lower index increases the critical angle of the emitted light and hence the overall extraction efficiency from the LED. The leakage current of the LED passivated with anAl₂O₃layer was-3.46 × 10⁻¹¹\ Aat$-$5 V, at least two and three orders lower in magnitude compared to that passivated with aSiO₂layer(-7.14 × 10⁻⁹\ A)and that of the nonpassivated LED(-1.9 × 10⁻⁸\ A), respectively, which indicates that theAl₂O₃layer is very effective in passivating the exposed GaN surface after dry etching and hence reduces the nonradiative recombination as well as reabsorption of the emitted light near the etched surface.