How does doping increase the conductivity of semiconductors?

(N/A) Doping involves adding small amounts of impurities to a semiconductor to modify its electrical properties.
$1$. When a semiconductor like $Si$ or $Ge$ is doped with electron-rich impurities (Group $15$ elements like $P$ or $As$),the extra valence electrons become delocalized,increasing conductivity. This is known as an $n$-type semiconductor.
$2$. When doped with electron-deficient impurities (Group $13$ elements like $B$ or $Al$),the crystal lattice develops electron vacancies called 'holes'. These holes allow electrons to move,thereby increasing conductivity. This is known as a $p$-type semiconductor.
Thus,doping introduces electronic defects that facilitate charge carrier movement,significantly enhancing electrical conductivity.