The material of LED chips
Products listed on our products page include the words ”AlInGaP”, “InGaN”, “AlGaAs” and so on. These words indicate the material combination of the LED chips.
Semiconductors of LED chips
LED is an abbreviation for Light Emitting Diode, which is a diode that uses semiconductors and emits light.
When it comes to semiconductors, silicon is a well-known material. But the energy emitted from the band gap of silicon is outside the range of visible light, and the much of band gap energy is released in a form other than light, so it is not often used in LEDs. Instead of silicon, Group III-V semiconductors, which are a combination of two types of elements, are mainly used.
Group III-V semiconductors include InN, GaAs, AlP and so on. They are combinations of elements such as nitrogen (N), phosphorus (P), and arsenic (As) with elements such as indium (In), aluminum (Al), gallium (Ga) and so on.
Mixing Semiconductors
Some semiconductors have a property that when mixed, the band gap energy changes in the intermediate region. Using this, any wavelength can be created by changing the mixing ratio.
However, this does not mean that it can be created at any mixing ratio.
When manufacturing LEDs, they are made by growing semiconductor crystals on a specific substrate. Crystals cannot grow unless the size of the lattice constant of the substance that makes up the substrate matches the size of the lattice constant of the semiconductor to be made, so the crystal must be made within a ratio that satisfies the lattice size conditions.
Furthermore, when electrons jump across a band gap in a semiconductor, there are two types: “direct” and “indirect”. The details will not be explained here, but direct band gap can emit energy directly as light, but indirect band gap has the characteristic that a part of the energy must be consumed as heat or the like. Therefore, it is considered desirable to manufacture LEDs at a mixing ratio that provides a direct transition as much as possible.
Ⅲ-Ⅴ Semiconductor Combinations
AlInGaP
By combining AlP and InP with conventional GaP, this combination succeeded in emitting light in the direct band gap, creating a highly efficient LED.
InGaN
This combination can efficiently emit wavelengths mainly from green to blue. Despite of many defects in its crystal structure, it has the property of being highly efficient in the blue region, and various studies are being conducted on it.
AlGaAs
This combination combines AlAs, which has an indirect band gap, and GaAs, which has almost the same lattice constant and has a direct band gap, and makes the emission wavelength variable in the direct band gap.
Finally
Through close cooperation with chip manufacturers, we are able to manufacture and provide LEDs using the most suitable chips to meet customer needs. If you are having trouble finding an LED manufacturer for general or special purposes, please leave it to Toricon Co., Ltd.
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