Electron excitation

Electron excitation is the transfer of a bound electron to a more energetic, but still bound state. This can be done by photoexcitation (PE), where the electron absorbs a photon and gains all its energy or by electrical excitation (EE), where the electron receives energy from another, energetic electron. Within a semiconductor crystal lattice, thermal excitation is a process where lattice vibrations provide enough energy to transfer electrons to a higher energy band. When an excited electron falls back to a state of lower energy, it undergoes electron relaxation. This is accompanied by the emission of a photon (radiative relaxation) or by a transfer of energy to another particle.

Electrons can be excited by photons, this is done by the electron absorbing a photon which causes the electron to move to an outer shell, however this only occurs if the energy of the photon that the electron absorb is equal to the energy levels required energy