Difference Between N Type and P Type Semiconductors

Materials classified as semiconductors have conductivities that are higher than those of insulators but lower than those of conductors. In other words, if a substance possesses 4 electrons in its outermost shell, it qualifies as a semiconductor. Intrinsic semiconductors and extrinsic semiconductors are the two basic categories into which semiconductor materials fall.

Extrinsic semiconductors may also be divided into two categories:

Semiconductor P-Type
Semiconductor N-Type

We shall compare P-type and N-type semiconductors in this article by taking into account a number of variables, including the kind of impurity introduced, the type of doping, the majority charge carriers, the density of charge carriers, the fermi level, etc. But first, let's define both types of semiconductors before getting into the specific differences between them.

Describe a Semiconductor

A material known as a semiconductor is often a solid chemical element or compound that, under certain circumstances, conducts electricity and has certain electrical characteristics. It is, therefore, perfect for regulating the electric current in electronics and appliances. Any material that has the ability to conduct electricity is referred to as a conductor, whereas materials that do not have this ability are referred to as insulators. Semiconductors possess characteristics that fall somewhere in the middle between conductor and insulator.

To create semiconductors, materials such as gallium arsenide or cadmium selenide, as well as pure elements like silicon or germanium, can be employed. Doping is a technique used to significantly alter the conductivity of pure semiconductors by introducing small amounts of impurities. Therefore, the dopants or impurities introduced to a semiconductor are what define its special characteristics.

Metals and other conductor materials theoretically have a band structure where the valence band and conduction band overlap, which makes metals easily conduct electricity. On the other hand, the comparatively large band gap between the valence band and the conduction band in insulators makes it difficult for electrons to join the conduction band.

In contrast, the space between the valence and conduction bands is quite narrow in semiconductors. Elevated temperatures allow for the efficient transition of electrons from the valence band to the conduction band. The semiconductor may conduct electricity after the electrons have managed to enter the conduction band.

In contrast to conductors, semiconductors' charge carriers only develop as a result of external heat energy. It results in a certain number of valence electrons passing over the energy barrier and moving into the conduction band, leaving a comparable number of holes in their wake. Both electron and hole-induced conductivity is significant.

Semiconductors' Features:

At zero Kelvin, semiconductors resemble insulators. On the other hand, they function as conductors when the temperature rises.
Due to their unique electrical properties, doping semiconductors can produce semiconductor devices suited for energy conversion, switches, and amplifiers.
Less power loss is offered by them
They are lighter and smaller in stature.
A semiconductor material's resistance goes down as the temperature rises and goes up in reverse when the temperature falls.

Different Semiconductor Types

1. Intrinsic Semiconductor

A semiconductor that is composed entirely of the semiconductor material is known as an intrinsic semiconductor.

Because it has a relatively small number of charge carriers-namely, holes and electrons-that it holds in equal amounts, it has an extremely low conductivity level. As a result, a semiconductor that is intrinsic can also be described as having the same amount of conduction electrons and holes.

The most prevalent types of intrinsic semiconductor materials are germanium (Ge) and silicon (Si), which both have four valence electrons (tetravalent) and are covalently linked to their atoms at absolute zero temperature.

A positively charged hole appears at its original location when the temperature rises because fewer electrons are freed to flow across the lattice. These unbound electrons and holes help the semiconductor conduct electricity. In the valence and conduction bands, respectively, holes and electrons travel in opposition to one another to produce semiconductor current.

2. Extrinsic Semiconductor

A semiconductor that has been doped with a particular impurity that can change its electrical characteristics is known as an extrinsic semiconductor. They are produced when intrinsic semiconductors are doped with a controlled amount of a chemical impurity called a dopant. This increases conductivity and makes the material suitable for optoelectronic applications like light emitters and detectors as well as electronic applications like diodes and transistors. Extrinsic semiconductors also fall under the categories of N-type and P-type semiconductors.

P-Type Semiconductor

A lot of holes are created in a pure semiconductor when a small quantity of trivalent (three valence electrons) impurities like gallium or indium are introduced to it, creating the P-type semiconductor. These p-type-producing impurities are known as acceptors because each of their atoms creates a hole that may accept a single-bound electron. The three valence electrons of the impurity combine with three of the four valence electrons of the semiconductor, resulting in a positive charge hole. Because the covalent connection cannot be completed due to the short electron, this hole is also referred to as a hole.

It is known as a p-type semiconductor, where p stands for positive since a very small amount of impurity includes a large number of atoms, leading to millions of holes, which are the semiconductor's positive charge carriers as a consequence.

In this semiconductor, holes make up the majority of the charge carriers, while electrons make up the minority. Since the hole has a larger density than the electron, the acceptor level is typically located nearer the valence band.

N-Type Semiconductors

A pentavalent (containing five valence electrons) impurity element is said to have been added to the N-type semiconductor, which is a form of extrinsic semiconductor. Pentavalent impurities or dopant elements are added to the N-type semiconductor to increase the number of electrons available for conduction.

The pentavalent impurities phosphorus, arsenic, and antimony are among the examples. To preserve the crystal integrity of the intrinsic base semiconductor, very little impurity is supplied to the N-type semiconductor. The pentavalent impurity atom forms covalent connections with four silicon atoms, leaving just one electron free. Donor impurities, such as pentavalent impurities, are so named because each of their atoms is thought to contribute one electron to an N-type semiconductor. As a result, the N-type semiconductor has more electrons than holes.

In an N-type semiconductor, the pentavalent impurity causes a large number of weakly bound electrons to occupy the lattice structure. These electrons gather energy to leave the valence band, bridge the forbidden gap and enter the conduction band if a sufficient level of voltage is applied. As a result, the valence band develops a relatively limited number of holes. As more electrons reach the conduction band, the Fermi level-the greatest energy level an electron can occupy at absolute zero-gets closer to the conduction band.

P-type and N-type Semiconductor Differences

The electrons gather energy to leave the valence band, bridge the forbidden gap and enter the conduction band if a sufficient level of voltage is applied. In order to better understand the differences between p-type and n-type semiconductors, additional factors are also taken into consideration. These include the density of electrons and holes, energy level and Fermi level, the direction of travel of the majority carriers, etc. The distinctions are explained in the following way:

The electrons in n-type semiconductors, which give them their name, have a negative charge, which is a key distinction. While in p-type, the absence of electron results in the generation of a positive charge, thus the term p-type.
The periodic table's III group element is introduced as a doping element in p-type semiconductors, whereas the V group element is used as a doping element in n-type semiconductors.
In an n-type semiconductor, electrons make up the bulk of carriers, while holes make up the minority.
In the n-type semiconductor, which is represented by ne>> nh, the electron density is significantly more than the hole density, whereas in the p-type semiconductor, nh >> ne, the hole density is significantly bigger than the electron density.
The donor energy level in an n-type semiconductor is far from the valence band and near the conduction band. The acceptor energy level is far from the conduction band and near the valence band in the p-type semiconductor.
Impurities added to p-type semiconductors result in additional holes known as acceptor atoms, whereas impurities introduced to n-type semiconductors result in additional electrons known as donor atoms.

Difference between P-Type and N-Type Semiconductors

Based on	P Type Semiconductor	N Type Semiconductor
Definition:	It is created when a trivalent impurity is introduced.	The semiconductor created when a pentavalent impurity is introduced to an intrinsic semiconductor is referred to as an N-type semiconductor.
Additional impurity class:	A trivalent impurity, such as aluminium, gallium, indium, etc., is introduced to the pure semiconductor to produce the P-type semiconductor.	To create an N-type semiconductor, pentavalent impurities like P, Sb, As, Bi, etc., are introduced to the pure semiconductor.
Group of doping elements:	To create a P-type semiconductor, atoms from group 13 are introduced as doping components.	To create an N-type semiconductor, the elements from group 15 are introduced as doping components.
Effect of impurity or doping element:	When an impurity is introduced to a P-type semiconductor, more holes are introduced.	The additional impurity gives the N-type semiconductor more electrons in the structure.
An additional term for the impurity	A trivalent element that can receive electrons from the intrinsic semiconductor serves as the doping element in P-type semiconductors. As a result, the term "acceptor impurity" also refers to the doping element or impurity.	Pentavalent atoms are employed as an impurity in N-type semiconductors to supply additional electrons. Therefore, the doping substance is often referred to as a donor impurity.
Majority charge carriers:	In a P-type semiconductor, holes make up the majority of charge carriers.	In an N-type semiconductor, the bulk of the charge carriers is electrons.
Minority charge carriers:	In a P-type semiconductor, the minority charge carriers are electrons.	In an N-type semiconductor, the minority charge carriers are holes.
Charge density:	In a P-type semiconductor, there are significantly more holes than electrons or Nh >> Ne.	In an N-type semiconductor, the ratio of electrons to holes, or Ne >> Nh, is substantially higher.
Majority charge carriers' migration:	Because they are positive holes, the majority of charge carriers in a P-type semiconductor migrate from a higher potential to a lower potential.	An N-type semiconductor travels from a lower potential to a higher potential because negative electrons carry the bulk of the charge.
Energy levels:	In a P-type semiconductor, the acceptor energy levels are incredibly close to the valance band while being distant from the conduction band.	Donor energy levels in N-type semiconductors are quite close to the conduction band while being distant from the valance band.
Conductivity:	The existence of holes in P-type semiconductors results in conductivity.	The existence of electrons is what gives the N-type semiconductor its conductivity.
Fermi level:	The Fermi level, which is situated in a P-type semiconductor between the acceptor energy level and the valance band, is known as the fermi state.	In an N-type semiconductor, the fermi level is situated below the conduction band.

Conclusion

Extrinsic semiconductors include P-type and N-type semiconductors. The main distinction between the two is that an N-type semiconductor is produced when pentavalent impurities like phosphorous are added to a pure semiconductor, whereas a P-type semiconductor is produced when a trivalent impurity like aluminium is added to a pure semiconductor.

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