In semiconductor physics, a donor is a dopant atom that, when added to a semiconductor, can form a n-type region.
For example, when silicon (Si), having four valence electrons, is to be doped as a n-type semiconductor, elements from group V like phosphorus (P) or arsenic (As) can be used because they have five valence electrons. A dopant with five valence electrons is also called a pentavalent impurity. [1] Other pentavalent dopants are antimony (Sb) and bismuth (Bi).
When substituting a Si atom in the crystal lattice, four of the valence electrons of phosphorus form covalent bonds with the neighbouring Si atoms but the fifth one remains weakly bonded. If that electron is liberated, the initially electro-neutral donor becomes positively charged (ionised). At room temperature, the liberated electron can move around the Si crystal and carry a current, thus acting as a charge carrier.
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[edit]References
[edit]- ^ "Fundamentals: Doping: n- and p-semiconductors". www.halbleiter.org. Retrieved 2016-12-19.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
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