Physics - Semiconductors Question with Solution | TestHub

A $n$-type semiconductor is formed by doping pure germanium or silicon crystal with suitable impurity atoms of valency five. As the impurity atoms take the position of Ge atom in germanium crystal, its four electrons form covalent bonds by sharing electrons with the neighbouring four atoms of germanium whereas the fifth electron is left free. Since the atom on the whole is electrically neutral, the $n$-type semiconductor is also neutral.