杂质半导体（英语：extrinsic semiconductor）又称外质半导体，是掺杂了杂质的半导体，即在本征半导体中加入掺杂物，使得其电学性质较无杂质半导体发生了改变。

掺杂过程涉及向本征半导体添加掺杂物原子，从而在达到热平衡的过程中改变电子和空穴这两种载流子的分布。根据杂质半导体中主要影响力的载流子，可以将半导体分为P型半导体和N型半导体。引入杂质后的半导体是很多电子器件的基础。

An extrinsic is a semiconductor that has been doped, that is, into which a doping agent has been introduced, giving it different electrical properties than the intrinsic (pure) semiconductor.

Doping involves adding dopant atoms to an intrinsic semiconductor, which changes the electron and hole carrier concentrations of the semiconductor at thermal equilibrium. Dominant carrier concentrations in an extrinsic semiconductor classify it as either an n-type or p-type semiconductor. The electrical properties of extrinsic semiconductors make them essential components of many electronic devices.