Optical simulation and fabrication of near-ultraviolet LEDs on a roughened backside GaN substrate

In this letter, the numerical and experimental demonstrations for enhancement of light extraction efficiency in near-ultraviolet light-emitting diodes (LEDs) with a roughened backside on the N-face surface of GaN substrate through a chemical wet-etching process are investigated. It was also found that the increased etching time can increase the height of hexagonal pyramids and decrease the density of hexagonal pyramids. With 20-mA injection current, it was found that forward voltages were 3.13 and 3.16 V while output powers were 13.15 and 27.18 mW for the conventional LED and roughened backside LED, respectively.