Enhancement of light extraction efficiency in InGaN/GaN vertical blue light emitting diodes by surface patterning: Design and simulation

Investigation of Photonic-Crystal-Structured p-GaN Nanorods Fabricated by Polystyrene Nanosphere Lithography Method to Improve the Light Extraction Efficiency of InGaN/GaN Green Light-Emitting Diodes

“…To increase the LEE of InGaN/GaN green LEDs, several methods based on reducing TIR between p-GaN and air were reported. The common techniques to enhance the LEE of GaN-based LEDs are use of pattern sapphire [ 16 , 17 , 18 ] and surface roughness [ 19 , 20 , 21 ]. Designed patterns such as hemisphere, pyramid, or hollow conical to reflect or modify the photons going to substrate direction are fabricated on a sapphire substrate through the etching process.…”

Control of LED radiation with functional dielectric metasurfaces

“…Artificial quasi-random porosity introduced by nanoimprint and etching techniques into the p-doped layer of GaN is compared with regular periodic PhC patterning in [24]; extracted light efficiencies for both structures display similar values, marginally higher for the porous design. Scatterers in surfaces of standard lateral or flip-chip LED configurations can be etched in different geometrical shapes: cylinders [25], (truncated) cones [26], hexagons [27], pyramids [28], blocks. All those have been shown to slightly improve the extraction efficiency, via different electromagnetic effect (distribution of charges, electric fields, guided modes, resonances, if any) occurring in the fabricated patterns.…”