Ferminivå

Ferminivå is a term used in solid state physics to describe the chemical potential of electrons in a material at a given temperature. It is commonly known as the Fermi level and represents the energy level at which the probability of occupation by an electron is significant according to the Fermi-Dirac distribution. At zero temperature, the Ferminivå corresponds to the highest occupied energy level in a system of non-interacting electrons; at finite temperatures, the occupancy around this energy is governed by thermal statistics.

In metals and degenerate semiconductors, the Ferminivå lies near the wing of the electronic structure where states are available for occupation, and it strongly influences electrical conductivity and carrier concentration. The position of the Ferminivå relative to the density of states determines how many electrons participate in conduction and how the material responds to external fields. The level can shift with changes in temperature, pressure, or composition, such as through doping, strain, or alloying.

In semiconductors, the Ferminivå provides a convenient reference for understanding intrinsic and doped materials. For intrinsic semiconductors, it lies near the middle of the band gap; n-type doping moves the Ferminivå closer to the conduction band, while p-type doping moves it toward the valence band. Measurements and calculations of the Ferminivå are essential for predicting electronic behavior, contact properties, and device performance in electronics and optoelectronics. Related concepts include the Fermi-Dirac distribution, chemical potential, and the density of states.