Optical microscopy images of polygonal LED chips operated at a bias voltage of 2.5 V; the center wavelength of emission is 470 nm.
Journal of Applied Physics, vol. 108, 2, pp. 023110 (2010)
The light extraction efficiencies of InGaN/GaN blue light-emitting diodes (LEDs) of different geometries ranging from a triangle to a decagon have been simulated by ray-tracing. The conventional rectangular LED was found to be the most inefficient among the investigated polygons, and light extraction through the device sidewalls was the key factor. The results were experimentally verified by fabricating LEDs shaped into polygons by nanosecond-pulsed laser micromachining, which proved the simulated results. The mechanism of light extrac-tion in polygonal LEDs is discussed in detail.
