Semiconductor Materials

00:19:28
https://www.youtube.com/watch?v=7jaa1rlW7Ak

Ringkasan

TLDRAquesta presentació se centra en l'inici de l'estudi de l'electrònica analògica, amb un èmfasi en materials semiconductors com el silici i el germani. Es revisen els conceptes de conductor, aïllant i semiconductor, basant-se en les seves propietats de conductivitat i resistivitat. El conductor permet un flux de corrent elevat quan s'aplica un voltatge, a diferència dels aïllants, que tenen una conductivitat molt baixa, com es veu en materials com la mica. Els semiconductors, clau per a dispositius electrònics, ocupen una posició intermediària quant a conductivitat. La resistivitat, inversa a la conductivitat, és crucial per determinar l'eficiència del pas del corrent. Els diagrames de bandes d'energia expliquen les transicions d'electrons entre bandes de valència i de conducció, sent fonamentals per a la comprensió de les propietats elèctriques de materials. A més, es discuteix la posició dels semiconductors en la taula periòdica i esmenta la rellevància de l'estructura cristal·lina del silici i el germani en la formació d'enllaços covalents.

Takeaways

  • 📘 Introducció a l'electrònica analògica.
  • 🔌 Diferència entre conductors, aïllants i semiconductors.
  • 💡 Importància del silici i germani com a semiconductors.
  • 📉 Explicació de resistivitat i conductivitat.
  • 📊 Diagrama de bandes d'energia per als materials.
  • ⚛️ Estructura atòmica dels semiconductors.
  • 🔬 Importància dels enllaços covalents.
  • 📐 Relació entre resistivitat i conductivitat.
  • 🌐 Posició del silici i germani a la taula periòdica.
  • 🧪 Influència de l'estructura atòmica en la conductivitat.

Garis waktu

  • 00:00:00 - 00:05:00

    La presentació comença amb una introducció a l'electrònica analògica, destacant la importància dels materials semiconductors com a fonament dels dispositius i circuits electrònics. Els temes coberts inclouen BJT, MOSFET, JFET i amplificadors operacionals (OPM). Inicialment, es distingeixen tres categories de materials segons la seva conductivitat: conductors (ex. coure, alumini), aïllants (ex. mica, fusta) i semiconductors (ex. silici, germani). S'explica la resistivitat del material com la inversa de la conductivitat, amb cada material mostrant valors específics segons la seva classe.

  • 00:05:00 - 00:10:00

    S'aprofundeix en la resistivitat de diversos materials: els conductors tenen una resistivitat baixa (10^-6 ohm·cm pel coure), aïllants com la mica tenen una resistivitat molt alta (10^12 ohm·cm), mentre que els semiconductors tenen una resistivitat intermediària (silici 50×10^3 ohm·cm, germani 50 ohm·cm). Això afecta el flux de corrent, sent menor pels aïllants i major pels conductors. Es passa a explicar el diagrama de bandes d'energia, on en àtoms aïllats el nivell més extern es divideix en bandes de valència i conducció, marcant el gap de banda d'energia prohibit, clau en la conducció.

  • 00:10:00 - 00:19:28

    Es discuteix el diagrama de bandes d'aïllants, semiconductors i conductors. Els aïllants presenten un gap de banda gran (aproximadament 6 eV), fent difícil la transició d'electrons entre bandes. Els semiconductors tenen un gap més petit, al voltant d'1 eV (germani 0.75 eV, silici 1.16 eV). En els conductors, les bandes de valència i conducció se superposen, permetent fàcilment el flux d'electrons. S'explora la taula periòdica per comprendre la posició del germani i silici, destacant la seva pertinença al grup 4 amb quatre electrons a l'òrbita externa, explicant la configuració estable mitjançant enllaços covalents entre àtoms de silici.

Peta Pikiran

Video Tanya Jawab

  • Què és un semiconductor?

    Els semiconductors tenen una conductivitat més gran que els aïllants però menor que els conductors.

  • Quins són dos materials semiconductors importants?

    Els materials semiconductors principals són el silici i el germani.

  • Què explica el diagrama de bandes d'energia?

    El diagrama de bandes d'energia explica les possibles transicions d'electrons dins d'un material.

  • Què és la resistivitat?

    La resistivitat mesura com un material s'oposa al flux de corrent.

  • Com determinen la resistivitat i els materials el flux de corrent?

    Els materials compleixen un rol selectiu, segons la seva resistivitat, en la conducció del corrent elèctric.

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Teks
en
Gulir Otomatis:
  • 00:00:05
    from this presentation we will start
  • 00:00:07
    analog electronics and in the first
  • 00:00:08
    lecture we will complete semiconductor
  • 00:00:11
    materials they are the backbone of
  • 00:00:13
    electronic devices and circuits that's
  • 00:00:15
    why it is very important to know what
  • 00:00:17
    are the different semiconductor
  • 00:00:19
    materials available to us and also their
  • 00:00:21
    properties so in this course we will
  • 00:00:24
    complete some topics like BJT mosfet jet
  • 00:00:28
    they are the Field Effect transist and
  • 00:00:30
    also the operational amplifiers in short
  • 00:00:33
    we call operational amplifier as OPM so
  • 00:00:36
    first we will complete the semiconductor
  • 00:00:38
    materials before going to diode and bjts
  • 00:00:41
    so let's start with it the first topic
  • 00:00:43
    is Conductor the term conductor is used
  • 00:00:45
    for any material that will support a
  • 00:00:47
    generous flow of charge when the voltage
  • 00:00:50
    is applied across the terminals we
  • 00:00:52
    already know the flow of charge through
  • 00:00:55
    a cross-sectional area in the given time
  • 00:00:57
    is called as current is called as
  • 00:01:00
    current and we have to check for the
  • 00:01:03
    amount of current flowing through the
  • 00:01:04
    material and depending upon this current
  • 00:01:06
    we will categorize them in three
  • 00:01:08
    categories the first one is Conductor
  • 00:01:10
    the second one is insulator and the
  • 00:01:12
    third one is semiconductor so let's
  • 00:01:14
    start with it I have taken two example
  • 00:01:16
    for the conductor the first one is the
  • 00:01:18
    copper wire and the second one is the
  • 00:01:19
    aluminium wire you must have seen them
  • 00:01:22
    in electrical equipments in your home
  • 00:01:24
    they are the most commonly used
  • 00:01:25
    conductors and if I cut this copper wire
  • 00:01:28
    I have a cross-section that will look
  • 00:01:30
    something like this so we have a
  • 00:01:31
    cross-sectional area a that is equal to
  • 00:01:33
    p piun r² and the amount of current
  • 00:01:36
    flowing through this cross-sectional
  • 00:01:38
    area in the given time is very high that
  • 00:01:40
    is the definition for the conductor the
  • 00:01:42
    flow of charge is very high when the
  • 00:01:43
    voltage applied across it terminals
  • 00:01:46
    whereas in case of insulator we have the
  • 00:01:50
    flow of current or you can say the
  • 00:01:52
    conductivity is very low when the
  • 00:01:54
    voltage is applied across the terminals
  • 00:01:56
    and the example that I have taken is MAA
  • 00:02:00
    is Mica and wood this Mica is very
  • 00:02:05
    important in electrical Industries it is
  • 00:02:08
    used for the thermal it is used for the
  • 00:02:12
    thermal and electrical and electrical
  • 00:02:14
    insulation in electrical equipment so it
  • 00:02:16
    is very important you must have seen it
  • 00:02:19
    and uh wood is definitely one of the
  • 00:02:21
    insulator so this is all for the
  • 00:02:23
    insulator the conductivity is really low
  • 00:02:26
    and you can say that the flow of charge
  • 00:02:28
    is nearly equal to zero in this case
  • 00:02:31
    let's move to the next thing that is our
  • 00:02:34
    semiconductor and the most important
  • 00:02:36
    thing that you must know in this course
  • 00:02:38
    so let's start with the semiconductor
  • 00:02:40
    what it is it is a material that has
  • 00:02:42
    conductivity more than the insulators
  • 00:02:44
    but less than the conductor very simple
  • 00:02:46
    that's why we call it semiconductor so
  • 00:02:49
    we can say that the flow of current in
  • 00:02:51
    semiconductor is not as much as the
  • 00:02:53
    conductor and not as low as the
  • 00:02:56
    insulator it is somewhere between the
  • 00:02:58
    conductor and insulator
  • 00:03:00
    and because of this only we call it
  • 00:03:02
    semiconductor the two most important
  • 00:03:04
    semiconductor material that you should
  • 00:03:07
    know are silicon and germanium silicon
  • 00:03:11
    is represented by Si and germanium is
  • 00:03:13
    represented by G they are very important
  • 00:03:16
    and we will see their properties in a
  • 00:03:18
    minute but before that I will talk about
  • 00:03:20
    the resistivity in this we will see the
  • 00:03:23
    resistivity
  • 00:03:25
    for the
  • 00:03:27
    resistivity for the conductor insulator
  • 00:03:30
    and semiconductor let's start with the
  • 00:03:34
    resistivity first what it is it is
  • 00:03:36
    represented by row and it is the
  • 00:03:39
    reciprocal for the conductivity Sigma is
  • 00:03:41
    the conductivity and row is the
  • 00:03:43
    resistivity and uh in terms of
  • 00:03:46
    resistance we can write resistivity as
  • 00:03:48
    row equals to R A by L where a is the
  • 00:03:53
    area of cross-section and L is the
  • 00:03:55
    length of the wire whose resistivity we
  • 00:03:57
    are measuring and it is the property of
  • 00:04:00
    the material this one is the
  • 00:04:06
    property of
  • 00:04:10
    material and for every material it is
  • 00:04:13
    fixed and for unit you can see we have
  • 00:04:17
    the ohm we have the ohm and we have
  • 00:04:20
    meter Square for area and um in
  • 00:04:24
    denominator we have meter for length so
  • 00:04:27
    the unit is mm
  • 00:04:30
    meter let's see the resistivity for the
  • 00:04:33
    conductor for conductor it is 10 ^ - 6
  • 00:04:40
    ohm CM you can see the resistivity is
  • 00:04:43
    very low and it is obvious that if
  • 00:04:46
    resistivity is high if resistivity is
  • 00:04:50
    high the current is going to be low
  • 00:04:52
    because the material is offering more
  • 00:04:55
    resistance whereas if resistivity is low
  • 00:04:58
    the current is going to be more because
  • 00:05:00
    the resistance offered by the material
  • 00:05:03
    is really low and for conductors we know
  • 00:05:06
    the flow of current is very high that's
  • 00:05:08
    why the resistivity is going to be low
  • 00:05:11
    and it is 10 ^ minus 6 and uh this one
  • 00:05:15
    this 10 ^ minus 6 is specifically for
  • 00:05:19
    the copper this one is for the copper
  • 00:05:23
    and as I have told you the resistivity
  • 00:05:25
    is the property of the material so it
  • 00:05:28
    may vary material aterial to material
  • 00:05:30
    for aluminium maybe it is different so
  • 00:05:33
    you have to write down in bracket that
  • 00:05:35
    it is for copper let's talk about the
  • 00:05:39
    insulator the insulator for Mica it is
  • 00:05:42
    10 ^
  • 00:05:44
    12 ohm
  • 00:05:46
    cm and you can see this is a huge amount
  • 00:05:49
    of resistivity 10 the^ 12 you can guess
  • 00:05:52
    what amount of resistance this material
  • 00:05:55
    is going to offer to the flow of charge
  • 00:05:58
    that's why we can say that the flow of
  • 00:06:00
    charge is negligible for Mica whereas if
  • 00:06:04
    I talk about the resistivity of the
  • 00:06:06
    Silicon it is 50 into 10 ^ 3 ohm cm and
  • 00:06:13
    for germanium it is 50 ohm CM so you can
  • 00:06:19
    clearly see that the resistivity for the
  • 00:06:21
    semiconductor let's say row s is the
  • 00:06:24
    resistivity of the semiconductor is less
  • 00:06:28
    than the resistivity
  • 00:06:29
    of the insulator so it is less than the
  • 00:06:32
    resistivity of insulator and it is
  • 00:06:36
    greater than the resistivity of the
  • 00:06:38
    conductor row C so this is the relation
  • 00:06:42
    that you must keep in your mind and
  • 00:06:44
    depending on this we have the flow of
  • 00:06:46
    current through this materials the flow
  • 00:06:48
    of current will be revers if I say
  • 00:06:52
    I is the flow of current for the
  • 00:06:55
    semiconductor then it is greater than
  • 00:06:59
    the insulator and less than the
  • 00:07:02
    conductor so this is all for the
  • 00:07:05
    resistivity now we will move to the next
  • 00:07:07
    topic that is the energy Bend diagram
  • 00:07:10
    I'm not going in much depth I will just
  • 00:07:12
    touch the surface of this energy Bend
  • 00:07:15
    diagram so let's see what is this energy
  • 00:07:17
    band diagram when the atom is isolated
  • 00:07:20
    let me draw the atom first this is the
  • 00:07:22
    nucleus having the neutrons and protons
  • 00:07:25
    and we have the orbits in which El Rons
  • 00:07:29
    are
  • 00:07:30
    present and we call this orbits as l m n
  • 00:07:35
    and so on and this outermost orbit will
  • 00:07:38
    have the valence electron because they
  • 00:07:41
    will participate in the chemical
  • 00:07:42
    reactions this is a simple model for an
  • 00:07:45
    isolated atom remember this one is the
  • 00:07:48
    isolated atom but in general the atom is
  • 00:07:50
    not isolated it is present in the
  • 00:07:52
    lettuce in case of silicon you can see
  • 00:07:56
    we have the lettuce in which the atom is
  • 00:07:59
    present
  • 00:08:00
    and uh it will form a particular
  • 00:08:02
    structure that we will see in a minute
  • 00:08:05
    and thus the neighboring atom will have
  • 00:08:07
    the influence on this atom as well this
  • 00:08:10
    atom will have some influence on the
  • 00:08:12
    neighboring atoms so what will be the
  • 00:08:14
    change because of the neighboring atoms
  • 00:08:16
    that we have to see this outermost orbit
  • 00:08:19
    will now split into the valance band and
  • 00:08:22
    the conduction band this one is the
  • 00:08:27
    valance band
  • 00:08:30
    and this one is the
  • 00:08:33
    conduction band so we have a splitted
  • 00:08:37
    outermost orbit and the electron present
  • 00:08:39
    in the conduction band will participate
  • 00:08:41
    in the conduction so if electron is
  • 00:08:43
    present in the valence band we have to
  • 00:08:46
    move this electron to the conduction
  • 00:08:48
    band and how we are going to do that the
  • 00:08:51
    only way to do that is to give this
  • 00:08:53
    electron some energy and the amount of
  • 00:08:56
    energy that we have to give this
  • 00:08:58
    electron must must be equal to this Gap
  • 00:09:01
    we call this energy band Gap or we call
  • 00:09:05
    it as the Forbidden band Gap we call
  • 00:09:08
    this forbidden band Gap because no
  • 00:09:10
    electron is allowed to stay in this
  • 00:09:13
    region that's why it is forbidden I will
  • 00:09:16
    represent this Gap by E
  • 00:09:18
    not and in some books they will
  • 00:09:20
    represent this Gap by EG so it doesn't
  • 00:09:24
    matter whatever representation you want
  • 00:09:27
    to use you can and in case of insulators
  • 00:09:31
    this is the energy band diagram
  • 00:09:35
    for insulators you can see it is very
  • 00:09:39
    large and hence the electron from the
  • 00:09:41
    valence band will require more energy to
  • 00:09:44
    go to the conduction B and participate
  • 00:09:47
    in the conduction that's why they are
  • 00:09:49
    not good conductors and they will not
  • 00:09:51
    allow the flow of charge and uh more
  • 00:09:56
    precisely e not is nearly equal to 6 6
  • 00:09:59
    electron volt for the insulators and you
  • 00:10:02
    already know 1 electron volt is equal to
  • 00:10:06
    1.6 into 10 ^
  • 00:10:09
    -9 jewles so you have to give six times
  • 00:10:13
    of this energy to make this electron
  • 00:10:16
    appear in the conduction band this is
  • 00:10:19
    for the insulators and if I talk about
  • 00:10:21
    the semiconductors definitely this band
  • 00:10:24
    is going to be much narrower and you can
  • 00:10:27
    see here we have reduced forbidden band
  • 00:10:31
    Gap and it is nearly equal to 1 electron
  • 00:10:36
    volt in case
  • 00:10:38
    of
  • 00:10:40
    semiconductors and uh if I talk about
  • 00:10:45
    germanium then it is
  • 00:10:47
    0.75 electron volt and in case of
  • 00:10:50
    silicon it is equal to
  • 00:10:53
    1.16 electron volt now you might be
  • 00:10:56
    thinking why in casee of germanium we
  • 00:10:58
    have 0.75 electron volt as the Forbidden
  • 00:11:01
    band Gap whereas in case of silicon it
  • 00:11:04
    is
  • 00:11:04
    1.16 geranium is having the lower energy
  • 00:11:09
    band Gap as compared to the Silicon
  • 00:11:12
    because of its atomic structure if you
  • 00:11:14
    see the atomic structure of geranium you
  • 00:11:16
    will find the number of orbits are more
  • 00:11:19
    and hence the force of attraction
  • 00:11:21
    between the valence electron and the
  • 00:11:22
    nucleus is smaller whereas in case of
  • 00:11:25
    silicon we have lesser number of orbits
  • 00:11:27
    and hence the force of attration is more
  • 00:11:30
    strong on the electrons so you have to
  • 00:11:33
    give more energy you can feel it like
  • 00:11:35
    electron is here and the nucleus is
  • 00:11:39
    pulling this electron towards itself and
  • 00:11:41
    you have to give energy to make this
  • 00:11:44
    electron appear in the conduction band
  • 00:11:46
    and depending upon the nucleus if it is
  • 00:11:49
    closer you have to give more energy if
  • 00:11:51
    it is far you have to give less energy
  • 00:11:53
    and in case of germanium the force of
  • 00:11:55
    attraction between the nucleus and the
  • 00:11:57
    electron is is smaller whereas in case
  • 00:12:00
    of silicon it is larger that's why we
  • 00:12:02
    have to give more energy in case of
  • 00:12:04
    silicon as compared to the germanium it
  • 00:12:07
    is very simple thing it is just pure
  • 00:12:09
    chemistry that you have studied in your
  • 00:12:11
    ninth standard now we can move to the
  • 00:12:14
    last type of material that we have to
  • 00:12:16
    see and it is
  • 00:12:20
    Conductor and you can see in case of
  • 00:12:23
    conductors the conduction band and the
  • 00:12:27
    valance band is overlapping there is no
  • 00:12:30
    forbid and bend Gap and thus the
  • 00:12:33
    conductivity is very high because
  • 00:12:35
    electron is free to go from Valance band
  • 00:12:38
    to conduction band and it will
  • 00:12:40
    participate in conduction without giving
  • 00:12:43
    any extra energy to it that's why the
  • 00:12:45
    conductivity is very high and this is
  • 00:12:48
    all about the energy band diagram and
  • 00:12:50
    you have one more definition to write in
  • 00:12:53
    your exam if someone ask you what do you
  • 00:12:55
    mean by the semiconductor you can easily
  • 00:12:57
    say that it is the Mater material in
  • 00:12:59
    which the Forbidden band Gap is nearly
  • 00:13:03
    equal to 1 electron volt whereas in case
  • 00:13:06
    of insulators it is nearly equal to 6
  • 00:13:08
    electron volt or more than it and in
  • 00:13:11
    case of conductors they overlap each
  • 00:13:13
    other so this is also a point that you
  • 00:13:16
    have to write in your exam now we will
  • 00:13:19
    see the periodic table so that we have a
  • 00:13:21
    better idea for the position of the
  • 00:13:24
    germanium and silicon and we can predict
  • 00:13:26
    some of the properties from this
  • 00:13:28
    periodic table so let's move to it this
  • 00:13:30
    is the periodic table and I hope you
  • 00:13:33
    know how to use a periodic table and in
  • 00:13:36
    what Manner the elements are distributed
  • 00:13:38
    to the different groups actually they
  • 00:13:40
    are distributed depending upon the
  • 00:13:42
    number of electrons in their outermost
  • 00:13:44
    orbit and in case of silicon and
  • 00:13:47
    germanium that you can see here this is
  • 00:13:50
    silicon and this one is germanium they
  • 00:13:52
    belong to group four and why they are in
  • 00:13:55
    group four because they have four
  • 00:13:57
    electrons in the outermost orbit you can
  • 00:14:00
    see in case of silicon the total number
  • 00:14:03
    of electron or the atomic number is 14
  • 00:14:06
    and you can have the electron in the
  • 00:14:10
    first orbit the maximum number of
  • 00:14:12
    electron in the first orbit equals to
  • 00:14:14
    two so we have two electrons in the
  • 00:14:16
    first orbit then we have eight electrons
  • 00:14:19
    so 2 + 8 is 10 and finally we have four
  • 00:14:22
    electrons so you can see four electrons
  • 00:14:24
    are there in the outermost orbit whereas
  • 00:14:27
    in case of germanium we have 32
  • 00:14:29
    electrons let's have two electrons in
  • 00:14:32
    the first orbit then 8 then 18 and then
  • 00:14:37
    four so germanium is also having four
  • 00:14:40
    electrons in its outermost orbit now
  • 00:14:43
    there is one very important thing that
  • 00:14:44
    you should keep in your mind that every
  • 00:14:47
    element will want to have a stable State
  • 00:14:50
    and for that they must have the noble
  • 00:14:53
    gas configuration this is the group for
  • 00:14:56
    the noble gas we have helium Neon Aron
  • 00:14:59
    Krypton Zenon redon and the Silicon will
  • 00:15:03
    try to have the configuration for Argon
  • 00:15:06
    that is the 18 electrons and germanium
  • 00:15:08
    will also try to have the configuration
  • 00:15:11
    for the Krypton that is 36 electron so
  • 00:15:14
    they need four more electrons to have
  • 00:15:16
    the noble gas
  • 00:15:17
    configuration and we will find a way so
  • 00:15:20
    that they will have four more electrons
  • 00:15:23
    the unique qualities of germanium and
  • 00:15:25
    silicon are due to their atomic
  • 00:15:27
    structure the atom of germanium and
  • 00:15:29
    silicon forms a definite pattern that
  • 00:15:32
    continuously repeats itself one complete
  • 00:15:35
    pattern is called Crystal and the
  • 00:15:37
    periodic Arrangement is called the
  • 00:15:39
    lettuce in this presentation when I make
  • 00:15:42
    the atomic structure for silicon I will
  • 00:15:44
    explain you what is this pattern and how
  • 00:15:47
    we can have this pattern by the calent
  • 00:15:51
    bond okay I will make the atomic
  • 00:15:54
    structure for silicon quickly this one
  • 00:15:58
    is the nucleus then we have our first
  • 00:16:03
    orbit and in this first orbit we have
  • 00:16:06
    two
  • 00:16:07
    electrons as I have already told you
  • 00:16:10
    then we will have our second
  • 00:16:14
    orbit and this second orbit will have
  • 00:16:17
    eight electrons let's make this eight
  • 00:16:21
    electrons
  • 00:16:24
    quickly it's like we are doing the
  • 00:16:26
    problem of ninth standard
  • 00:16:29
    but these things are really important in
  • 00:16:31
    analog Electronics so we have two
  • 00:16:33
    electrons and then eight electrons in
  • 00:16:36
    total we have 10 we need four more
  • 00:16:38
    electrons to make 14
  • 00:16:42
    electrons this is circular I'm not
  • 00:16:45
    making it
  • 00:16:46
    circular so let's add four more
  • 00:16:51
    electrons okay so this is the atomic
  • 00:16:54
    structure for silicon and we want to
  • 00:16:57
    have four more electrons in this silicon
  • 00:17:00
    so that it attains the noble gas
  • 00:17:02
    configuration to do that we will make a
  • 00:17:04
    covalent bond we have three types of
  • 00:17:06
    bond the first one is the ionic bond or
  • 00:17:10
    electrovalent bond in which the donation
  • 00:17:12
    of the electron is done you will donate
  • 00:17:14
    the electron to some other entity
  • 00:17:17
    completely whereas in case of coent bond
  • 00:17:21
    we just share the electron so we are
  • 00:17:24
    going to see
  • 00:17:26
    how by the calent bond
  • 00:17:29
    Bond we can have the eight electrons in
  • 00:17:32
    the outermost orbit I will copy it down
  • 00:17:36
    and then I will paste
  • 00:17:38
    it
  • 00:17:40
    okay I will
  • 00:17:42
    copy and paste
  • 00:17:45
    again now you can see now you can see we
  • 00:17:49
    can have the covalent bond between this
  • 00:17:53
    two
  • 00:17:54
    electrons and this two
  • 00:17:57
    electrons and we have we have to
  • 00:17:59
    focus to this particular atom we don't
  • 00:18:02
    have to see for this two atoms we will
  • 00:18:04
    see for this atom we will try to have
  • 00:18:06
    eight electrons in the outermost orbit
  • 00:18:08
    of this atom only for now and uh you can
  • 00:18:11
    see we have
  • 00:18:13
    one 2 3 this electron is shared 4 5 6
  • 00:18:22
    okay so we have six electrons we need
  • 00:18:25
    two more so I'm going to
  • 00:18:27
    paste
  • 00:18:28
    one more silicon
  • 00:18:30
    atom and finally the last one
  • 00:18:35
    here and I will make two more coent
  • 00:18:38
    bonds taking this two electrons and this
  • 00:18:42
    two electrons so we have seven and eight
  • 00:18:45
    so we have eight electrons for this
  • 00:18:47
    silicon atom and this is the pattern
  • 00:18:50
    that I was talking about and this is one
  • 00:18:52
    complete pattern and uh more patterns
  • 00:18:56
    like this will make our lettuce and that
  • 00:18:58
    lettuce is used in the diode bjts and
  • 00:19:02
    other electronic devices so we are
  • 00:19:04
    moving to the important topics real
  • 00:19:07
    quick you have to keep this
  • 00:19:10
    configuration in your mind it will help
  • 00:19:12
    you to understand intrinsic and
  • 00:19:14
    extrinsic semiconductors so this is all
  • 00:19:17
    we are already pushing our time in the
  • 00:19:19
    next presentation we will study about
  • 00:19:22
    the intrinsic and extrinsic
  • 00:19:24
    semiconductor as well as the electron
  • 00:19:26
    and hole concept
Tags
  • electrònica analògica
  • materials semiconductors
  • conductivitat
  • resistivitat
  • diagrama de bandes