LED Light Extraction

Much of the light generated by an LED is reflected back into semiconducting material itself (internal reflection) and is lost as heat. The result is lower light output, and heat removal problems. There are two ways to improve light extraction:

1. Selective GaN Etching (GaN Roughening)

A rougher semiconductor surface disrupts internal reflection, allowing more light to escape. GaN is roughened using alkaline etchants such as KOH. Patterned, sacrificial coatings are needed to protect exposed metal traces during GaN roughening.

Products: ProTEK^® PSB coating

2. High–Refractive Index Materials

Coatings having a refractive index from 1.7 to 2.0 will minimize internal reflection by bridging the large difference in refractive index between the semiconductor and the encapsulant materials. Such index matching techniques significantly improve light extraction.

Products: OptiNDEX™ Coatings