Boron, arsenic, and antimony, among other substances, are used as dopants when added to a pure semiconductor material to alter its electrical characteristics.
Artificially produced gemstones[?] (such as Ruby (gemstone)) usually contain a dopant to identify them as such.
... elected on the same ticket by popular vote for four-year terms. The president has extensive executive powers and is both head of state and head of government and he also ...