distinguish between intrinsic and extrinsic semiconductor
Distinguish between intrinsic and extrinsic semiconductor
Answer:
An intrinsic semiconductor is a pure semiconductor material that has no impurities added to it. It is made up of a single element or compound with a well-defined crystal structure. Intrinsic semiconductors, like silicon (Si) and germanium (Ge), have their valence band completely filled with electrons and their conduction band empty at absolute zero temperature. However, at room temperature, a few electrons are thermally excited to the conduction band, creating electron-hole pairs. The conductivity of intrinsic semiconductors is relatively low due to the low concentration of charge carriers.
On the other hand, an extrinsic semiconductor is a semiconductor material that has impurities deliberately added to it. This process is known as doping and it is done to modify the electrical properties of the material. Doping introduces impurity atoms of different valence electrons into the crystal lattice of the semiconductor. The two types of doping are n-type and p-type.
In n-type doping, a small amount of a group V element such as phosphorus or arsenic is added to the intrinsic semiconductor. These impurity atoms have more valence electrons than the semiconductor atoms, creating excess electrons in the conduction band, making it an effective n-type (negative) charge carrier. N-type doping increases the conductivity of the semiconductor.
In p-type doping, a small amount of a group III element such as boron or gallium is added to the intrinsic semiconductor. These impurity atoms have fewer valence electrons than the semiconductor atoms, creating “holes” in the valence band. These holes behave like positive charge carriers and effectively increase the conductivity of the semiconductor. P-type doping creates p-type (positive) charge carriers.
In summary, intrinsic semiconductors are pure semiconducting materials, while extrinsic semiconductors have impurities intentionally added to modify their electrical properties. Extrinsic semiconductors can be either n-type or p-type, depending on the type of dopant added.