section_path: Categories/Semimetal
section_name: Semimetal
paragraph_text: Semimetal
  
  A semimetal is a material with a small energy overlap between the bottom of the conduction band and the top of the valence band, but they do not overlap in momentum space. Unlike a regular metal, semimetals have charge carriers of both types (holes and electrons), so that one could also argue that they should be called 'double-metals' rather than semimetals. However, the charge carriers typically occur in much smaller numbers than in a real metal. In this respect they resemble degenerate semiconductors more closely. This explains why the electrical properties of semimetals are partway between those of metals and semiconductors. There are additional types, in particular Weyl and Dirac semimetals.
  
  The classic elemental semimetallic elements are arsenic, antimony, bismuth, α- tin (gray tin) and graphite. There are also chemical compounds, such as mercury telluride (HgTe), and some conductive polymers can behave as semimetals.