Hint:These categories of semiconductors are based on how the doping is carried out. So think about the ways of doping and try to figure out the difference between these two. The materials which have an electrical conductance between that of an insulator and a conductor is known as semiconductor.
Complete answer: Semiconductor are typically group fourteen elements(C, Si, Ge).Each silicon atom is bonded with four neighbouring silicon atoms. Silicon has four electrons in its valence shell. Each one of these electrons goes for sharing with a neighbouring silicon atom and forms a covalent bond.
The electrons are in their valence band. If the pure silicon has to conduct electricity. The electrons have to absorb some energy and become free electrons. Thus, pure silicon will have a low electrical conductivity. In the pure form they are called intrinsic semiconductors.Doping is the process of adding impurities to the pure form of semiconductor. Let’s see the difference between two methods of doping
Pentavalent impurity atoms(five valence electrons) are added such as phosphorus, arsenic.
Trivalent impurity atoms(three valence electrons) are added such as boron,gallium.
Due to the addition of pentavalent atoms, one electron will be free to move in the system.
Due to the addition of trivalent atoms, A hole is created in the system, a place where there should be an electron but there is not. It still increases the conductivity of the silicon because electrons can move into these holes.
This is known as n-type semiconductor because electrons(negative charges) are moving and conducting the current.
Although it is the electrons that are moving, we usually say holes are moving around. And since the hole is the lack of an electron, it actually acts as a positive charge and this is why it is called a p-type semiconductor.
Note:Semiconductors are employed in the manufacturing of various types of electronic devices like transistors, diodes etc. They have countless applications. To increase the conductivity of semiconductors, we do doping.