What is a semiconductor? Describe the two main types of semiconductors and contrast their conduction mechanism.

Explanation

Semiconductors: Those elements whose conductivity increases with an increase in temperature are called semiconductors. There are two types of semiconductors:
Intrinsic semiconductors: Pure substances that are semiconductors are called intrinsic semiconductors. For example. germanium and silicon are intrisic semiconductors.
Extrinsic semiconductor: Semiconductors whose properties are largely determined by impurities are called extrinsic semiconductors. For example, silicon doped with phosphorus is an extrinsic semiconductor.
Silicon doped with phosphours is called n-type semiconductor because conductivities is determined by the presence of negative charge (electrons). Silicon doped with gallium is called p-type semiconductor because the conductivity is determined by positive hole.