Types of Semiconductor Materials | Intrinsic & Extrinsic Semiconductor | Engineering Funda
Summary
TLDRThis engineering video delves into semiconductor materials, distinguishing between intrinsic and extrinsic types. Intrinsic semiconductors, like pure silicon, have low conductivity due to a lack of free charge carriers, but their conductivity increases with temperature as electron-hole pairs are generated. Extrinsic semiconductors, in contrast, have higher conductivity due to added impurities. N-type materials are doped with pentavalent impurities, introducing extra electrons, while P-type materials incorporate trivalent impurities, creating holes. The video explains how these impurities define the number of free electrons and holes, affecting the material's conductivity and temperature coefficient.
Takeaways
- đ Semiconductor materials are categorized into intrinsic and extrinsic types, with the former being pure and the latter having added impurities.
- đ Intrinsic semiconductors, such as pure silicon, have lower conductivity due to the absence of free charge carriers, as all electrons are involved in covalent bonds.
- đĄïž The conductivity of intrinsic semiconductors increases with temperature because thermal energy can break covalent bonds, generating electron-hole pairs.
- âŹïž Intrinsic semiconductors exhibit a negative temperature coefficient, meaning their resistivity decreases as temperature increases due to the generation of more free charge carriers.
- đ Examples of intrinsic semiconductor materials include silicon and germanium, which are widely used in electronic devices like chips.
- đ Extrinsic semiconductors have higher conductivity than intrinsic ones because impurities introduce additional free charge carriers.
- đŹ N-type semiconductors are created by adding pentavalent impurities like phosphorus, which donate free electrons, increasing conductivity.
- đ§ P-type semiconductors are formed by introducing trivalent impurities like aluminum, which create vacancies or holes that act as free charge carriers.
- đ Both n-type and p-type semiconductors are used in various electronic applications, with n-type materials having electrons as majority carriers and p-type having holes as majority carriers.
- âïž Covalent bonds in semiconductors can be broken not only by increasing temperature but also by applying a high potential difference or a strong electric field, leading to the generation of electron-hole pairs.
Q & A
What are the three categories of solid materials mentioned in the script?
-The three categories of solid materials mentioned are conductors, semiconductors, and insulators.
What is an intrinsic semiconductor material?
-An intrinsic semiconductor material is a pure semiconductor material with no impurities added, such as pure silicon or germanium.
How does the conductivity of intrinsic semiconductor materials compare to extrinsic semiconductor materials?
-Intrinsic semiconductor materials have lower conductivity compared to extrinsic semiconductor materials because they do not have additional free charge carriers.
What happens to the conductivity of intrinsic semiconductors when the temperature increases?
-As the temperature increases, electron-hole pairs are generated, which increases the number of free charge carriers and thus increases the conductivity.
What is the term for the phenomenon where resistivity decreases with an increase in temperature in intrinsic semiconductors?
-The phenomenon where resistivity decreases with an increase in temperature is called a negative temperature coefficient.
What are the two basic types of extrinsic semiconductor materials?
-The two basic types of extrinsic semiconductor materials are n-type and p-type.
Which impurities are added to create n-type semiconductor material, and why?
-Pentavalent impurities, such as phosphorus or arsenic, are added to create n-type semiconductor material because they have five electrons in their outer orbit, which results in an extra free electron and thus increases conductivity.
How do trivalent impurities contribute to the formation of p-type semiconductor material?
-Trivalent impurities, such as aluminum or boron, contribute to the formation of p-type semiconductor material by creating vacancies or holes in the electron structure, which increases the number of free holes and conductivity.
What is the term for impurities that add free electrons in n-type semiconductors?
-The term for impurities that add free electrons in n-type semiconductors is 'donor impurities' because they donate an extra electron.
What is the term for impurities that add free holes in p-type semiconductors?
-The term for impurities that add free holes in p-type semiconductors is 'acceptor impurities' because they accept an electron, creating a hole.
What are the three ways mentioned in the script to generate electron-hole pairs in semiconductor materials?
-The three ways to generate electron-hole pairs in semiconductor materials are by increasing temperature, applying a higher potential difference across the material, or applying a higher electric field through the material.
Outlines
đŹ Introduction to Semiconductor Materials
The paragraph introduces the topic of semiconductor materials, contrasting them with conductors and insulators. It explains that semiconductors can be classified into intrinsic and extrinsic types. Intrinsic semiconductors are pure, without added impurities, and have lower conductivity compared to extrinsic semiconductors, which have impurities added to increase their conductivity. The concept of energy bands in materials is referenced, and the role of temperature in generating free charge carriers in intrinsic semiconductors is discussed. Silicon is given as an example of an intrinsic semiconductor material, with its four electrons in the outer orbit forming covalent bonds with neighboring atoms, resulting in no free charge carriers at 0 Kelvin. As temperature increases, electron-hole pairs are generated, which can increase conductivity. The negative temperature coefficient of intrinsic semiconductors is highlighted, meaning that as temperature rises, resistivity decreases due to the generation of more free charge carriers.
đ Extrinsic Semiconductor Materials and Conductivity
This paragraph delves into extrinsic semiconductor materials, which are created by adding impurities to pure semiconductors, resulting in higher conductivity. The unit of measurement for impurities, parts per million (PPM), is introduced. The paragraph explains the difference between n-type and p-type semiconductors. N-type materials have pentavalent impurities added, which contribute an extra electron, making them donor impurities and increasing the number of free electrons, thus enhancing conductivity. Examples of n-type impurities are phosphorus and arsenic. On the other hand, p-type materials have trivalent impurities added, which create vacancies or holes, making them acceptor impurities. Aluminum and boron are cited as examples of p-type impurities. The paragraph also discusses how the majority charge carriers in n-type materials are electrons, while in p-type materials, they are holes. The effect of temperature on the generation of electron-hole pairs is also mentioned, as well as the fact that the majority carriers in extrinsic semiconductors are determined by the type of impurity added.
đ© Understanding P-Type Semiconductor Materials
The final paragraph focuses on p-type semiconductor materials, which are formed by adding trivalent impurities with three electrons in their outer orbit. This addition results in the creation of holes or vacancies in the electron structure, which are referred to as acceptor impurities because they can accept electrons. The paragraph explains that these holes are the majority charge carriers in p-type materials, while electrons are the minority carriers. The process of how covalent bonds can be broken, leading to the generation of electron-hole pairs, is discussed in three scenarios: increasing temperature, applying a higher potential difference, or applying a higher electric field. The paragraph concludes by summarizing the basics of semiconductor materials and inviting viewers to ask questions or share comments for further clarification.
Mindmap
Keywords
đĄSemiconductor
đĄIntrinsic Semiconductor
đĄExtrinsic Semiconductor
đĄCovalent Bonds
đĄElectron-Hole Pair
đĄNegative Temperature Coefficient
đĄN-Type Semiconductor
đĄP-Type Semiconductor
đĄImpurities
đĄConductivity
Highlights
Introduction to semiconductor materials and their classification into intrinsic and extrinsic types.
Explanation of intrinsic semiconductors as pure materials with no impurities added.
Description of silicon as a prime example of an intrinsic semiconductor material.
Discussion on the lower conductivity of intrinsic semiconductors compared to extrinsic ones.
Explanation of how electron-hole pairs are generated in intrinsic semiconductors at increased temperatures.
The concept of negative temperature coefficient in intrinsic semiconductors.
Examples of intrinsic semiconductor materials, such as silicon and germanium.
Introduction to extrinsic semiconductors and their higher conductivity due to impurities.
Definition and role of impurities in defining the number of free electrons and holes in extrinsic semiconductors.
Explanation of n-type semiconductors with the addition of pentavalent impurities.
Details on how phosphorus impurities contribute to the creation of free electrons in n-type materials.
Introduction to p-type semiconductors with the addition of trivalent impurities.
Role of aluminum impurities in creating free holes in p-type semiconductor materials.
Discussion on donor and acceptor impurities in n-type and p-type semiconductors, respectively.
Explanation of majority and minority charge carriers in n-type and p-type semiconductors.
Mechanisms for breaking covalent bonds in semiconductors through temperature, potential difference, and electric field.
Summary of the basics of semiconductor materials and their practical applications.
Transcripts
Hello friends welcome to engineering
Panda family in this video I am going to
explain you types of semiconductor
material
in my last video I have explained you
how we have classification of solid
material we have been having three
categories conductor semiconductor and
insulator
and I have already explained how energy
bands are there with material in my last
video
in this video I'll explain you how
semiconductor materials are there so
when you want to classify semiconductor
material then there are in general two
categories
intrinsic semiconductor material and
extrinsic semiconductor material
intrinsic semiconductor material is a
pure semiconductor material PR means
there is no impurities added with
semiconductor
while with expensive semiconductor
material we add some impurities
let us try to understand Basics first
after that I'll explain you how
impurities are added and what will
happen based on impurities so see with
intrinsic semiconductor material we are
having pure semiconductor material and
you need to understand one thing see
with pure semiconductor material we will
be having lower conductivity compared to
extrinsic semiconductor material how we
can have lower conductivity that even
I'll explain you but first of all you
need to understand what is pure
semiconductor material If You observe
one example of silicon then silicon is
pure semiconductor material in Silicon
in its outer orbit there are four
electrons and those four electrons are
connected with their neighbor atom if
you consider this silicon that is having
let us say these four electrons are
there right
you can observe here four electrons are
there
so these four electrons are connected
with covalent bonds you can observe see
these four electrons
of this atom that is connected with
covalent bonds with their neighbor atom
so you can say all the electrons are
connected in covalent bond structure and
as all the electrons are connected in
covalent bond structure you can say here
there is no free charge carrier in pure
silicon and pure silicon that is
referred as intrinsic semiconductor
material and it is having lower
conductivity I'll show you why it is
having lower conductivity
see at 0 Kelvin temperature there are no
free charge carriers and as there are no
free charge carriers conductivity will
be less but as you increase the
temperature there is a possibility that
electron holes pair that will get
generated let me show you how it will
happen
If You observe here see here we are
having electrons right these are
connected in covalent bonds so as if I
say this electron that is getting out of
this covalent bond and let us say this
electron become free
let us say this electron become free
so what will happen here here there will
be generation of holes
here there will be generation of holes
right so as you increase the temperature
it is possible this covalent bond this
covalent bond that will get
break and as if covalent bond is getting
break then three electron will get
generated and at this place there will
be whole right so here there is electron
hole pair generation as if you increase
temperature at 0 Kelvin there is no free
charge carrier but as you increase
temperature recharge carriers that will
get generated over here right
it has equal number of free electrons
and holes why the reason is all the
electrons are connected in covalent bond
if one electron is getting free then
there will be one hole right see
electron is having negative charge whole
is having positive charge that is how we
consider things right so here equal
number of holes and equal number of
electrons will be there
it has negative temperature coefficient
now what is the meaning of negative
temperature coefficient see here if you
increase the temperature if you increase
the temperature then resistivity will go
down why resistivity will go down if you
increase the temperature free electron
hole pair that will get generated inside
material and as if you have free charge
carriers in the material then that its
resistivity that will go down
right so here
with intrinsic semiconductor material we
have negative temperature coefficient
what it means if you increase the
temperature
recharge carrier will get generated and
because of free charge carriers
resistivity will go down here some basic
examples that I have written
with intrinsic semiconductor material we
can have silicon and germanium widely
this two semic these two semiconductor
materials are widely used
practically silicon that you will be
observing most of the chips are using
silicon right
here let us discuss about x26
semiconductor material first
see in pure semiconductor material if we
add impurities then it will become in
extrinsic semiconductor material right
see due to impurities it is having
higher conductivity I'll show you
practically how it will be having higher
conductivity right now just consider due
to impurities
extrinsic semiconductor material will be
having higher conductivity here
impurities will Define number of free
electrons and holes I'll show you that
even how it will define it
here we are adding impurities in the
unit of PPM
part per million so in terms of PPM we
add impurities see for example part per
million means as if I say one PPM
impurity is added then one atom of
impurity that we added per 1 million of
pure atoms that is how unit is there
right and basic example of actronic
semiconductor material are n type and P
type
now I am going to explain you how
impurities are added and how n-type and
p-type material is there so if You
observe basic silicon structure that we
have now in this basic silicon structure
with n-type material
we are adding pentavalent impurities so
Here If You observe here I have added
phosphorus impurity and phosphorus is
having five phosphorus is having five
electrons in its outer orbit usually
with silicon how many electrons are
there with outer orbit 4. so here
additional electron that we are adding
right so four electrons that will get
combined with this ovalent Bond but one
electron that will stay free over here
so in n-type material in N type material
we add pentavalent impurities
pentavalent impurities means Phi
electrons in its outer orbit with
silicon we have four electrons in its
outer orbit so as you add five electrons
impurity pentaval and impurity so you
will be adding three electrons so as you
add
impurities over here you are adding free
charge carriers right and as you add
free charge carriers what will happen
obviously conductivity will increase
right I have told you you see intrinsic
semicondable material is having lower
conductivity why the reason is by
default free charge carriers are not
available but in extrinsic semiconductor
material we add impurities that leads to
higher conductivity why the reason is in
pure silicon in pure silicon if you add
pentavalent impurities it will add free
electrons right in p-type semiconductor
material we add trivalent impurities
tribal and impurities means three
electrons will be there in its outer
orbit so what will happen if You observe
here I have added aluminum so aluminum
is having three electrons in its outer
orbit silicon structure is having four
electrons in its outer orbit so what
will happen one electron space will be
vacant over here and that is referred as
three hole over here so as you add
tribal and impurities
in p-type material you are adding free
holes and in n-type material you are
adding free electrons so practically we
are adding free charge carriers that
leads to higher conductivity in
extrinsic semiconder material like
n-type and P type right now let us
discuss about some basics of n-type and
P type ce9 type we add pentavalent
impurities means in its outer orbit Phi
electrons will be there
so with every impurity one free electron
is added and that's why it is also
referred as donor impurity donor
impurity means here we are donating one
extra
recharge carrier as electron right
here impurities can be formed from group
of five like phosphorus and anti-money
so in n-type semiconductor material
practically we add phosphorus and
anti-money
here majority charge carrier with n type
that will be electrons why the reason is
number of impurities will leads to
number of free electrons so here with
this material majority charge carriers
will be electrons and as you increase
the temperature
some electrons will go out of this
covalent bond and it will generate
electron hole pair that may leads to
holes but minority carriers will be
holes over here with pure semiconductor
material with pure semiconductor
material electron and holes are equal
but with n-type semiconductor material
we are adding additional impurity with
additional electron so here majority
carriers will be electrons and minority
carriers will be holes now when you want
to understand how P type semitender
material is there then in p-type
seminary material we add tribal and
impurities which is having three
electrons in its outer orbit and because
of that what we do we are adding
additional free hole means electron
space is vacant that is referred as
pre-hole right as if electron space is
vacant that is referred as pre-hole so
you can say here we are adding three
holes over here with impurities
and this is also referred as acceptor
impurity why it is referred as acceptor
impurity the reason is this whole this
hole is having tendency to accept the
electron this hole is having tendency to
accept the electron that's why it is
also referred as acceptor impurities
some examples that I have listed here
impurities from third group that could
be aluminum or Boron right so here we
can have herd group impurities like
aluminum and Boron here majority charge
carriers will be holes as we add
trivaland impurities over here and
minority charge carriers those are
electrons over here and those minority
carriers can be generated because of
covalent bond is getting break due to
some reason now if you want to
understand how covalent bond is getting
break in any semiconductor material then
all you need to do is you need to
increase the temperature for example if
you apply heat if you apply heat to this
material then these electrons will break
covalent bond and it will get free so as
if electron is getting free over here it
will generate electron hole pair right
there is one another way by which you
can have breaking of covalent bond
you can apply higher potential
difference in between two terminal of
material by which we can generate
electron hole pair and Third Way is by
applying higher electric field through
the material if you apply higher
electric field through the material then
also you can generate electron hole pair
over here so this is how
Basics are there with semiconductor
material I hope you have understood this
still if anything that would like to
share please note it down in comment
section I'll be happy to help you thank
you so much for watching this video
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