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Home > FAQ > Epitaxy > For 4” pss wafer, the light comes out from the p-GaN side not from sapphire, so I can't do flip chip packaging. Also I don't know whether laser liftoff is possible for pss wafer.

Q:For 4” pss wafer, the light comes out from the p-GaN side not from sapphire, so I can't do flip chip packaging. Also I don't know whether laser  liftoff  is possible for pss wafer.

Is it possible you can share any image of the etched surface of pss?

 

A: 4"LED wafer on pps also can be LLO(NL-buffer layer is GaN). Again,LED light is sourcing from mqw light, emitting in all directions, p-GaN is positive(front side), it will naturally light, also each backside will light.At the bottom of the sapphire is also light, and then through the reflected light from other angles