Q:Our application will be making micro-pillar arrays based on the MQWs for high brightness LEDs and its wavelength tuning. So we do not really care the emission wavelength you provide but we will mind whether the process and emission wavelength would be consist between wafers in one pack as well as the uniformity in one wafer. No metal contact would be perfect as we will employ high temperature process in our application. Do you offer the wafer dicing service as well? A:You require good uniformity between wafer and wafer, also you require good uniformity in one wafer.From you application, you need patterned sapphire substrate with epi layers, (flat sapphire with epi layers is not available).You said you cut chip size 1cm*1cm, I guess you mean: you want 45mil chip size, and then list an array, such as: 10pcs*10pcs of 45mil chip size.Because if for single chip size>=1cm, the brightness is not as good.Because LED have droop effect.
Q:We are using 40x40 mil size and 45x45 mil size chips for 1W . And 45x22 or 38x22mil size for 0,5w . Eff. is min. 120lm/w , package form is 3535 ceramic no lens flat type, and 5050 smd flat type.Cct 6500k, cri min 70-75, drive current 350 mA ( it can be change if you have suggest for it ), can you give us suggestion? A:We suggest you choose our LED wafer on PSS substrate, EL wavelength(wafer):455+/-2.5nm, 70% yield rate.
Q:Is it possible to use 4” non-patterned sapphire for fabrication? A:Not possible, currently all the manufacturers swift to patterned sapphire based wafer, including us, however if you really need flat sapphire based wafer, we we can offer 2" size.
Q:The ideal waverlength for us is 465 nm, can you offer?. A:It is no problem, but you should know the wavelength should be a range, what we will offer you 465+/-2nm.
Q:What is the minimum batch size for blue LED wafers on 4 inch sapphire (patterned sapphire)? A:5pcs is ok, but the price would be higher.
Q:For blue wafer epi on flat substrate, it would be important to omit / leave out the u-GaN layer as we want to LLO and backside conacting. Is that possible? A:Yes, it is no problem, some clients bought our wafers for LLO.
Q:Do these 2” PSS LED wafers have the same epi-stack as the 4” PSS? If not, please send me the diagram with thicknesses. Wavelength can be same: central 455nm A:the 2" detail layer thickness and structure is same as 4", no any difference. Wavelength:455nm+/-5nm is no problem.
Q:I am not sure whether practically LLO can be done on the PSS given it is not a flat surface A:"laser lift-off" actually is according to "NL layer" as below image. If the NL layer is GaN layer, when it is heating to constant high temperature, the GaN is decomposed into Ga and nitrogen, and nitrogen is released out, naturally the sapphire is seperated from epitaxial layer.So the main point is if the NL layer is GaN layer or not (some manufacturers use NL layer by AlN material, if so, it can not be laser lift off.)And we confirm our NL layer is GaN material.