Fabrication of epitaxial wafer:
Red-yellow epitaxial wafer and Blue-green epitaxial wafer
Blue-green epitaxial wafer is 2" GaN epitaxial wafer, grown
on sapphire substrate by MOCVD (Metal-Organic Chemical Vapor Deposition).
The layer structure consisted of n-type layer, light emitting layer
of InGaN-GaN multi-quantum well, and p-type layer. The wavelength
of InGaN-GaN MQW is between 360nm and 550nm, cover blue wave band
and green wave band, so it becomes the ideal material for blue-green
LED. In addition, the n-type GaN and p-type GaN are used as cathode
and anode contact layer separately.
Red-yellow epitaxial wafer is grown on GaAs substrate. The layer
structure consisted of DBR reflect mirror, n-type blocking layer,
light emitting layer of MQW, p type blocking layer and GaP window
layer, etc. The wavelength of the epitaxial wafer is decided by the
MQW. Different colors from 560 to 650 can be obtained by adjusting
the Al concentration of AlGaInP MQW.
Fabrication of LED chip:
LED chips are made by epitaxial wafer through cleaning, lithographic
process, vapor deposition, etching, lapping electrode, polishing,
dicing. Sorted by intensity, wavelength, forward voltage, reverse
voltage, then the different optic and electric classified LED chips
obtained. Each epitaxial wafer can be made 20,000 to 70,0000 chips
by different size, mostly used for display screen, indicator light,
nixie light, city illumination, etc.
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