1. Substrate

• Material: Commonly used sapphire (Al₂O₃), silicon (Si) or silicon carbide (SiC).
• Function: It provides the basis for the growth of epitaxial layer and affects the heat dissipation and luminescence efficiency.
• Features: sapphire low cost, but poor thermal conductivity; Silicon carbide conducts heat well, but costs a lot.

2. Buffer Layer

• Material: Usually aluminum nitride (AlN) or gallium nitride (GaN).
• Function: Reduce the lattice mismatch between substrate and epitaxial layer, improve crystal quality.

3. N-type Layer

• Material: Gallium nitride (GaN) doped with silicon (Si).
• Function: Provides electrons to form part of the PN junction.

4. Quantum Well

• Material: Aluminum gallium nitride (AlGaN) multilayer structure.
• Action: Electrons and holes are combined here to emit light, determining the wavelength of light.
• Features: By adjusting the aluminum content of AlGaN, the wavelength of UVC light is controlled (200-280nm).

5. P-type Layer

• Material: Gallium nitride (GaN) doped with magnesium (Mg).
• Function: Provide holes to form another part of the PN junction.

6. Electrodes

• Material: Commonly used gold (Au) or silver (Ag).
• Structure:
• N-type electrode: located on the N-type layer, usually a negative electrode.
• P-type electrode: located on the P-type layer, usually positive.
• What it does: It provides an electric current to ensure that electrons and holes are combined to glow in quantum Wells.

7. Reflective Layer

• Material: Commonly used aluminum (Al) or silver (Ag).
• Function: Reflect light, improve light output efficiency.

8. Encapsulation

• Material: commonly used silica gel or epoxy resin.
• Function: Protect the chip, improve light efficiency and durability.