Periodic variation in the electroluminescence intensity on a single pattern from InGaN/GaN light-emitting diodes fabricated on lens-shaped patterns

We investigated the spatial distribution of light emission from InGaN/GaN light-emitting diodes (LEDs) fabricated on lens-shaped patterns (LSPs) by using confocal scanning electroluminescence microscopy (CSM). From three-dimensional CSM images measured by varying the position of the focal plane of a detector, the luminescence profiles from the InGaN/GaN LEDs were significantly changed with respect to the position of the LSP itself. In addition, it the EL intensity around the boundary region of the single LSP was found to fluctuate periodically with the distance of 671 nm between the adjacent bright patterns. From the simple theoretical analysis, the periodic fluctuation around the boundary of every single pattern in the CSM images is attributed to interference effects due to periodically-positioned LSPs.