An extrinsic semiconductor is a type of semiconductor material that has been doped with impurities to alter its electrical conductivity/Semiconductors/Extrinsic_Semiconductors). During the manufacture of the semiconductor crystal, a trace element or chemical called a doping agent is incorporated chemically into the crystal for the purpose of giving it different electrical properties than the pure semiconductor crystal, which is called an intrinsic semiconductor. The doping agents used are of two types, resulting in two types of extrinsic semiconductor: n-type and p-type.

• N-type semiconductor: In an n-type semiconductor, a pentavalent impurity such as phosphorus is added to an intrinsic semiconductor such as silicon or germanium. The impurity atoms act as donors, providing excess electrons that become the majority carriers in the crystal.

• P-type semiconductor: In a p-type semiconductor, a trivalent impurity such as boron is added to an intrinsic semiconductor. The impurity atoms act as acceptors, creating holes in the crystal that become the majority carriers.

Extrinsic semiconductors are used to make semiconductor electronic devices such as diodes, transistors, integrated circuits, semiconductor lasers, LEDs, and photovoltaic cells. The conductivity of an intrinsic semiconductor depends on the surrounding temperature, and it exhibits low conductivity at room temperature, making it unsuitable for use in electronic devices. Doping is the process that changes an intrinsic semiconductor to an extrinsic semiconductor, and the atoms that are used as an impurity are termed as dopants.