Energy Band Diagram of Intrinsic Semiconductor

Difference Between Intrinsic and Extrinsic Semiconductor

Given Below is the Energy band diagram of the Intrinsic Semiconductor

In this diagram we can see that with the finite temperature the probability of existing the electron in the conduction band will decrease exponentially with respect to the increase in the band gap(Eg).

[Tex]n=n_oe^{-E_g/2.Kb.T}[/Tex]

In the given equation,

Eg is the Energy band gap

Kb is the Boltzmann’s constant

Extrinsic Semiconductors

Extrinsic semiconductors are intentionally doped with impurity atoms to alter their electrical properties and increase their conductivity. Doping involves introducing a small number of foreign atoms into the crystal lattice of the intrinsic semiconductor. The most common dopants are from Group III (trivalent) and Group V (pentavalent) elements.

There are two main types of extrinsic semiconductors, depending on the type of dopant used:

N-type Semiconductors
P-type Semiconductors

N-type Semiconductors

In N-type Semiconductors, the semiconductor material is doped with atoms from Group V of the periodic table, such as phosphorus (P) or arsenic (As). These dopant atoms have one extra valence electron compared to the semiconductor material. When they replace some of the semiconductor atoms, they create extra electrons in the crystal lattice.

Conductivity is mainly because of electrons.
The material is entirely neutral.
The current (I) is due to electron current (Ie), and the concentration of electrons (ne) is much greater than that of holes (nh).
Majority carriers are electrons, and minority carriers are holes.

P-type Semiconductors

In order to form p type Semiconductor, trivalent impurity is added to it. These elements have three electrons in there valence shell and need 1 more electron. These are from Group III of the periodic table, such as Boron (B) or Aluminum (Al). These dopant atoms have one less valence electron compared to the semiconductor material. When they are added in semiconductor atoms they take one electron and create holes in the crystal lattice.

Conductivity is mainly because of the holes.
The material is entirely neutral.
The current (I) is due to hole current (Ih), and the concentration of holes (nh) is much greater than that of electrons (ne).
Majority carriers are holes, and minority carriers are electrons.

Formation of PN Junction by N and P type Semiconductor

PN Junction Forward Bias

Creating P and N type Semiconductor by doping: P type semiconductor can be formed by doping the pure semiconductor such as germanium or silicon by adding impurities In P type Group 3 elements are added such as boron Aluminium. N type semiconductor can be made by adding impurities from atoms of Group 5 such as arsenic or phosphorus.
Bringing the created N and P type Semiconductor together: We need to take the p and n type semiconductor closer in order to form PN Junction. The free electrons of negative N type region will move towards the P type semiconductor and the holes move in opposite direction towards n type region. The holes and the electrons recombine with each other a form a region where no free mobile charge carriers(charge carriers which have movement ) are present it is known as depletion region.

In a forward bias, when a positive voltage is applied to the P-side and negative voltage to the N-side, the potential barrier is reduced, and current can flow across the junction. In reverse bias, where the P-side is negative and the N-side is positive, the potential barrier increases, and the junction prevents significant current flow.

Semiconductors

A Semiconductor is a kind of material that performs conductivity between conductors and insulators and has a conductivity value that lies between the conductor and an insulator.

In this article, we will be going through semiconductors, first, we will start our article with the introduction of the semiconductor, then we will go through holes and electrons with band gap theory, and after that we will go through properties and types of semiconductors, At last, we will conclude our article with solved examples, applications and advantages with some FAQs.

Table of Content

Holes and Electrons
Direct and Indirect Band Gap Semiconductors
Properties of Semiconductor
Types of Semiconductor
Intrinsic Vs Extrinsic Semiconductors
Applications of Semiconductor
Advantages of Semiconductor
Disadvantages of Semiconductor
Examples of Semiconductor