Effect of packing density and packing geometry on light extraction of III-nitride light-emitting diodes with microsphere arrays
نویسندگان
چکیده
The finite-difference time-domain method was employed to calculate light extraction efficiency of thin-film flip-chip InGaN/GaN quantum well light-emitting diodes (LEDs) with TiO2 microsphere arrays. The extraction efficiency for LEDs with microsphere arrays was investigated by focusing on the effect of the packing density, packing configuration, and diameter-to-period ratio. The comparison studies revealed the importance of having a hexagonal and close-packed monolayer microsphere array configuration for achieving optimum extraction efficiency, which translated into a 3.6-fold enhancement in light extraction compared to that for a planar LED. This improvement is attributed to the reduced Fresnel reflection and enlarged light escape cone. The engineering of the far-field radiation patterns was also demonstrated by tuning the packing density and packing configuration of the microsphere arrays. © 2015 Chinese Laser Press OCIS codes: (230.0230) Optical devices; (250.0250) Optoelectronics. http://dx.doi.org/10.1364/PRJ.3.000184
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