: In semiconductors, photons with energy below the "band gap" are not absorbed at all, making effectively zero for those wavelengths.
(alpha), it describes the probability of absorption per unit length of the material. absorption coefficient
The is a fundamental physical parameter that quantifies how effectively a medium absorbs energy—typically in the form of light or sound—as it passes through. Represented by the Greek letter : In semiconductors, photons with energy below the
Understanding the Absorption Coefficient: A Comprehensive Guide : In semiconductors