WannierMottexciton

Wannier-Mott excitons are quasi-particles that form in semiconductors and insulators when an electron and a hole (a positively charged quasi-particle) bind together. This binding occurs due to the attractive Coulomb interaction between the negatively charged electron and the positively charged hole. The term "Wannier-Mott exciton" is named after Gregory Wannier and Nevill Mott, who first described this phenomenon in the 1930s.

In a semiconductor, excitons can be formed through various processes, such as optical absorption of light, where a photon excites an electron from the valence band to the conduction band, leaving behind a hole. The electron and hole can then attract each other and form an exciton. In insulators, excitons can be formed through thermal or quantum fluctuations.

Wannier-Mott excitons are characterized by their large binding energy, which can be on the order of several hundred millielectronvolts. This binding energy is much larger than the thermal energy at room temperature, which means that excitons can exist as stable quasi-particles even at high temperatures. The binding energy of a Wannier-Mott exciton depends on the effective mass of the electron and hole, as well as the dielectric constant of the material.

Wannier-Mott excitons play an important role in the optical and electronic properties of semiconductors and insulators. They are responsible for phenomena such as photoluminescence, where an exciton recombines and emits a photon. Excitons also play a role in the transport of charge carriers in semiconductors, and their properties can be used to engineer new materials with desired optical and electronic properties.