How does light move electrons from the valence band to the conduction band in a semiconductor?

In a semiconductor, light facilitates the movement of electrons from the valence band to the conduction band through a process known as the internal photoelectric effect.12

This process occurs when incident light photons possess energy ($h\nu$) that is greater than or equal to the material's bandgap ($E_g$). When a photon with sufficient energy strikes an electron in the valence band, the electron absorbs that energy and is excited across the bandgap into the conduction band.21

This transition results in the creation of a hole—a region of missing negative charge—in the valence band. Together, the newly freed electron in the conduction band and the hole in the valence band act as charge carriers, which increases the material's electrical conductivity. The specific energy required for this transition varies by material; for instance, silicon requires approximately 1.12 eV, a threshold that falls within the range of infrared and visible light.132