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
Q:What wafer size do you provide epi wafer with flat sapphire substrate for green light? A:Currently we still can offer 2" wafer on flat sapphire substrate.
Q:Regarding blue LED epi wafer, after MOCVD, do you anneal the wafer for p-GaN activation? A:Yes!
Q:The epitaxial wafer on pss substrate is attractive to me, so I want to know the overall efficiency it can deliver. Could you please tell me an efficiency number (lm/w or cd/A or EQE) of the device based on a structure similar to the picture in your email? A:Please see attached spec on chips.
Q:Regarding LED epi wafer,does the price include fabrication of p and n metal contacts? If not, can you fabricate p and n contacts plus SiO2 passivation based on my design? This can turn to a bigger project. A:Sorry, we can not offer fabrication of p and n metal contacts, also we can not fabricate p and n contacts plus SiO2 passivation.
Q:What is the highest temperature and the highest thermal shock that the wafers can withstand? A:At the temperatures higher than 1000 C on the free surface of Si-face of 6H-SiC (0001) the carbon segregation properties are started so that during short time the thin carbon layer is appeared due to Si escape from surface layer. (If the heatihg on the air, the carbon interacts with oxygen and carbon layer is not appeared, only oxide layer (SiO2) formed.) On the C-face (000-1), this processes are started from 600-700 C.Near the pipes, these properties can be started at the more low temperatures!