Metaalhalfgeleiders

Metaalhalfgeleiders, also known as metallic semiconductors or semimetals, are a class of solid materials that exhibit electrical conductivity between that of a typical metal and a semiconductor. Unlike conventional semiconductors where the valence and conduction bands are separated by a band gap, in metaalhalfgeleiders, these bands overlap infinitesimally. This overlap results in a small number of charge carriers (electrons and holes) being present at absolute zero temperature, leading to a unique combination of metallic and semiconducting properties.

The electronic band structure is key to understanding metaalhalfgeleiders. The Fermi level lies within the overlapping region of the valence and conduction bands. This means that a small amount of energy is sufficient to excite electrons from the valence band to the conduction band, similar to semiconductors. However, the pre-existing overlap ensures that there are always charge carriers available, even at very low temperatures, which is characteristic of metals.

Common examples of metaalhalfgeleiders include graphite, bismuth, antimony, and arsenic. Their electrical resistivity is generally higher than that of pure metals but much lower than that of typical semiconductors. They also often display unusual properties such as a strong diamagnetism or a high thermoelectric effect. These unique characteristics make metaalhalfgeleiders interesting for research and potential applications in areas like spintronics, thermoelectric devices, and advanced sensor technology. Their behavior can also be sensitive to pressure and magnetic fields, further contributing to their scientific intrigue.