Light Extraction Enhancement of a GaN-Based Light-Emitting Diode Through Grating-Patterned Photoelectrochemical Surface Etching With Phase Mask Interferometry

The enhancement of light extraction by fabricating a surface grating structure around the mesa of a light-emitting diode (LED) with an approach combining photoelectrochemical (PEC) wet etching and phase mask interferometry is demonstrated. The PEC etching rate is controlled by the intensity of illuminating UV light, which is spatially modulated by the fringe pattern of phase mask interferometry, for forming the grating structure. Without affecting the resistance characteristics of the device, the diffraction of such a grating structure leads to LED output enhancement by > 43% on either the top or bottom side.