Semimetal

<p>A semimetal is a material with a small energy overlap between the bottom of the <a href="/facts/Electrical_conduction/akyCKvMy">conduction</a> <a href="/facts/Electronic_band_structure/W5o7oE2R">band</a> and the top of the <a href="/facts/Valence_band/2NUALlHJ">valence band</a>, but they do not overlap in <a href="/facts/Momentum_space/kxKPCeoI">momentum space</a>. According to <a href="/facts/Band_theory/W5o7oE2R">electronic band theory</a>, solids can be classified as <a href="/facts/Insulator_(electricity)/SfSXkrh5">insulators</a>, <a href="/facts/Semiconductor/zFf3mGTE">semiconductors</a>, semimetals, or <a href="/facts/Metal/PT8hNX6R">metals</a>. In insulators and semiconductors the filled valence band is separated from an empty conduction band by a <a href="/facts/Band_gap/IjIeh95l">band gap</a>. For insulators, the magnitude of the band gap is larger (e.g., > 4 <a href="/facts/Electronvolt/YMT1fqX9">eV</a>) than that of a semiconductor (e.g., < 4 eV). Because of the slight overlap between the conduction and valence bands, semimetals have no band gap and a small <a href="/facts/Density_of_states/bwVTyhTf">density of states</a> at the <a href="/facts/Fermi_level/WpyRA0V7">Fermi level</a>. A metal, by contrast, has an appreciable density of states at the Fermi level because the conduction band is partially filled.
</p>

Semimetal open-in-new

Semimetal