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What is the color visible to the naked eye UV-C LED Visible part of the emission spectrum, It comes from oxygen substitution sites in semiconductor materials, Electronic transitions between various deep energy levels such as lattice mismatch dislocations and conduction band energy levels. Because the defect energy level is located higher relative to the quantum well valence band, So the photons emitted by electronic transitions have longer wavelengths, usually 450nm left and right, For visible light. Restricted by the accuracy of semiconductor equipment, Chips from different regions and batches on the wafer, The concentration of material defects, There are slight differences in defect categories. This difference results in a difference in the position of deep energy levels that emit visible light, Further emit visible light of different wavelengths, Presenting different colors. Although the wavelength difference is very small, But it is noticeable to the naked eye.