Explain why crystalline silicon is opaque to visible light w

Explain why crystalline silicon is opaque to visible light, while diamond is transparent. Identify the data you need and find the values on the Web.

Solution

Both diamond and silicon have the same structure but their apearance is different. Diamond(insulator with energygap greater than 4eV) is transparent to visible light because its electrons are unable to accept the low energy photons of visible spectrum and so fail to react with the passage of light in this frequency range.As the energy gap of silicon(semiconductor) is 1.1ev silicon crystal is opaque to visible light but is transparent to lower energy infrared radiation.