Improved output power of InGaN LEDs by lateral overgrowth on Si-implanted n-GaN surface to form air gaps

In this paper, air gaps were embedded in the n-GaN layer to improve light output power of InGaN-based light-emitting diodes (LEDs). Si ions ⁺²⁸ were implanted on the n-GaN surface, causing a lattice constant disorder. Therefore, the GaN grown on the Si-implanted areas had a lower growth rate than the implantation-free regions. Without using a dielectric thin film, lateral epitaxial overgrowth technique was used to form air gaps above the implanted regions and below the active layers of InGaN LEDs. We proposed the growth mechanisms of GaN layer on the Si-implanted GaN templates and characterized the InGaN-based LEDs with embedded air gaps array. With a 20-mA current injection, experimental results indicate that light output power (LOP) of the proposed LEDs was enhanced by 36%, compared with those of the conventional LEDs. This enhancement can be attributed to the light scattering at the textured GaN/gap interfaces to increase the effective light escape cone in the LEDs. Based on ray tracing simulation, if the height and the width of bottom of gaps were increased to 3 μ, the Lop could be enhanced over 70%.