Blue LED crystal growth can be sapphire and silicon carbide (SiC) as a substrate material, because the high price of
silicon carbide substrate, so the production of GaN-based light emitting diodes, more commonly applied to the sapphire substrate. Sapphire substrate with cheap, high hardness, high temperature resistance, chemical corrosion properties, but low thermal and electrical properties, the LED poor performance, but because of the low-power LED thermal limited, so sapphire substrate at low power market advantage.
Since the sapphire substrate itself is not electrically conductive, thus InGaN grown on the sapphire substrate above the element electrodes are fabricated using the element must be on the same side, and the SiC substrate may be electrically conductive, so do the two electrodes of the LED edge, the grains size can be reduced, thus reducing the cost of grain, making it easier to package.
LED substrate material selection, the main consideration is that the degree of similarity of the epitaxial layer material on the substrate lattice mismatch and thermal expansion coefficient with the substrate, defects in the epitaxial layer as long as the lattice parameter of the substrate material and the matching degree is higher, the epitaxial layer is produced fewer. A high degree of lattice constant matching SiC substrates, more suitable for the production of GaN epitaxy, and SiC substrates in addition to the degree of lattice matching sapphire substrate is better than the outside, because the SiC semiconductor material itself, suitable for use in semiconductor processing technology processing, thus using semiconductor fabrication processes, the geometry of the silicon carbide substrate is treated to reduce the phenomenon of total internal reflection of light in the grains, the grains that the extraction efficiency can be greatly improved.
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| sapphire substrate |
Since the sapphire substrate itself is not electrically conductive, thus InGaN grown on the sapphire substrate above the element electrodes are fabricated using the element must be on the same side, and the SiC substrate may be electrically conductive, so do the two electrodes of the LED edge, the grains size can be reduced, thus reducing the cost of grain, making it easier to package.
LED substrate material selection, the main consideration is that the degree of similarity of the epitaxial layer material on the substrate lattice mismatch and thermal expansion coefficient with the substrate, defects in the epitaxial layer as long as the lattice parameter of the substrate material and the matching degree is higher, the epitaxial layer is produced fewer. A high degree of lattice constant matching SiC substrates, more suitable for the production of GaN epitaxy, and SiC substrates in addition to the degree of lattice matching sapphire substrate is better than the outside, because the SiC semiconductor material itself, suitable for use in semiconductor processing technology processing, thus using semiconductor fabrication processes, the geometry of the silicon carbide substrate is treated to reduce the phenomenon of total internal reflection of light in the grains, the grains that the extraction efficiency can be greatly improved.
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