Improving the −3 dB bandwidth of medium power GaN-based LEDs through periodic micro via-holes for visible light communications

Medium power GaN-based light emitting diode (LED) chips with periodic micro via-holes are designed and fabricated. The active area of each chip is 200 µm×800 µm and the diameter of each micro via-hole is 50 µm. For comparison, an LED chip with only one big via-hole (Diameter=86.6 µm) is also fabricated under the same conditions as the control partner. Both kinds of LED chips have an equal effective PN junction area. Experimentally, the LED with periodic via-holes exhibits higher output optical power and the −3 dB modulation bandwidth by about 33% and 48%, respectively, than the LED with only one bigger via-hole. The method of concurrently improving modulation and optical performances of power-type LED chips through periodic micro via-holes take the advantages of easy fabrication, suitable for mass-production.