Types of Semiconductors
Based on the number of electrons and holes, there are two types of semiconductors: Instrinc and Extrinsic
Intrinsic semiconductor
A semiconductor in which the number of electrons is equal to the number of holes is known as an intrinsic semiconductor. It is also known as a pure semiconductor because there exists no impurity that has been added to this semiconductor.
Condition for intrinsic / Pure semiconductor: ne = nh = ni
where ne = number of electrons
nh = number of holes
ni = intrinsic carrier concentration
As the number of electrons and holes are equal in the intrinsic semiconductor, it is electrically neutral.
At room temperature, the conductivity of intrinsic semiconductors is very low, and it is not fit for designing any practical devices.
Extrinsic Semiconductor
As we all know, based on conductivity, we divide the material into three categories: Conductor, Semiconductor, and Insulator. In which the conductivity of the conductor is highest, insulators have the lowest conductivity, and semiconductors have intermediate conductivity. The reason behind this is the number of free electrons present in the crystal of each material. If we talk about the conductivity of semiconductors, two different types of semiconductors are classified based on the number of electrons and holes present in the crystal: Intrinsic and Extrinsic semiconductors. In this article, we will discuss these semiconductors, especially extrinsic semiconductors, their properties, formation, needs, and various applications.
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