Electrondoping

Electrondoping is a process used to increase the number of free electrons in a material, typically a semiconductor. This is achieved by introducing atoms of a different element into the crystal lattice of the original material. These introduced atoms, known as dopants, possess more valence electrons than the atoms of the host material. When these dopant atoms are incorporated into the lattice, their extra valence electrons become delocalized and contribute to the electrical conductivity of the material. The most common host materials for electrondoping are elements from Group 14 of the periodic table, such as silicon and germanium. Dopants used for electrondoping are typically elements from Group 15, like phosphorus, arsenic, or antimony, which have five valence electrons. In a silicon crystal, which has four valence electrons per atom, a phosphorus atom will substitute for a silicon atom. Four of the phosphorus atom's valence electrons form covalent bonds with neighboring silicon atoms, while the fifth electron is weakly bound and easily excited into the conduction band, becoming a free charge carrier. This type of doped semiconductor is called an n-type semiconductor, where "n" stands for negative, referring to the charge of the dominant charge carriers, the electrons. Electrondoping is a fundamental technique in the fabrication of electronic devices, including diodes, transistors, and integrated circuits, as it allows for precise control over the electrical properties of semiconductor materials.