Semiconductors

26
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Semiconductors

Transcript of Semiconductors

  • 1

  • 2

    Si: 0.543 nm

  • 3

    sp3 , r. ,

  • 4

    Si , Ge GaAs

    Si: , EG= 1.12 eV

  • 5

    Ge : L , EG= 0.67 eV

    GaAs : EG= 1.43eV

  • 6

    E-k

    12

    2 2

    1n

    Emk

    = =

    12

    2 2

    1p

    Emk

    = =

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    Fermi

    ( ) /

    1( )e 1FE E kT

    f E = +

    Fermi-Dirac

    . Fermi

    ( )

    Maxwell-Boltzmann

    ( ) .

  • 8

    1.5kT Fermi

    100( ) /MB FD MBf f f = Fermi Maxwell-Boltzmann

    10%.

    :

    3 3V F CE kT E E kT+ :

    1( )

    ex p [( ) / ] 1F D Ff E

    E E kT= +

    ( ) ex p [ ( ) / ]M B Ff E E E kT =

  • 9

    ( ) ( )t o p

    C

    E

    C C bE

    f E g E d E N n = =

  • 10

    :

    [1 ( )] ( )V

    bottom

    E

    V VbE

    f E g E dE N p = = :

    3/ 2

    2 3 3

    2 ( ) 8 2( ) n n C nC Cm m E E mg E E

    h

    = = =

    :

    3/ 2

    2 3 3

    2 ( ) 8 2( ) p p V pV V

    m m E E mg E E

    h

    = = =

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    :

    2 3

    21 exp[( ) / ]

    top

    C

    En n C

    CbF

    m m E E dEn N

    E E kT = = =+ =

    2 30

    21 exp[( ) / ]

    n n C

    F

    m m E E dEE E kT

    = + = 2 3

    0

    2exp[( ) / ]

    exp[( ) / ]n n C

    C F CF

    m m E E dEN E E kT

    E E kT = =

    3/ 2

    22 2n

    Cm kTN = =

    . :

    3/ 2

    2exp[( ) / ] 2 exp[( ) / ]2p

    V V F V F

    m kTp N E E kT E E kT

    = = =

    3/ 2

    22 2p

    V

    m kTN

    = = .

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    n p :

    exp[( ) / ] exp[( ) / ]C F C V V Fnp N E E kT N E E kT= =i

    exp[( ) / ] exp( / )C V V C C V GN N E E kT N N E kT= = ni = pi :

    3/ 2exp( / 2 ) exp( / 2 )i i C V G Gn n p N N E kT AT E kT= = = =

    5/ 2 3/ 2

    21 3 3/ 23

    2 ( ) 4.83 10 /m kA m Kh = =

    Fermi

    exp[( ) / ] exp[( ) / ]i i C F C V V Fn p N E E kT N E E kT= =

    ln 2C C V FV

    NkT E E EN

    = +

    1/ 21 ( ) ln2

    VF C V

    C

    NE E E kTN

    = + +

    1/ 21 ( ) ln2

    pF C V

    n

    mE E E kT

    m = + +

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    1 ( ) ( )2F C V C V p n

    E E E N N m m= + = =

    ( )n pe n p = +

    ( ) ( 1) ni i n i p i pp

    e n p en b b = + = + =

    ( 1) exp( / 2 )i p C V Ge b N N E kT = + =

    3/ 2

    22 ( 1) exp( / 2 )2p n

    p G

    m m kTe b E kT

    = + = =

    exp( / 2 )GC E kT= H C :

    n

    p

    b = , 3/ 2

    p T , 3/ 2n T

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    2

    ( ) (0)g gaTE T E

    T = +

    GaAs EG(0) (eV) 0.7437 1.166 1.519 (meV/K) 0.477 0.473 0.541

    () 235 636 204

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    3/ 2exp( / 2 ) exp( / 2 )i C V G Gn N N E kT AT E kT= = =

    3/ 4 3/ 219

    0 0

    (2.510 10 ) exp( / 2 )300

    pnG

    mm T E kTm m

    =

    200 700 :

    4 7 2

    0

    1.028 (6.11 10 ) (3.09 10 )nm T Tm

    = +

    4 7 2

    0

    0.610 (7.83 10 ) (4.46 10 )pm

    T Tm

    = +

    ni, mn/m0 , mp/m0 (m0

    )

    .

    .

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    ( )

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    ( ):

    11 exp[( ) ]2

    DD

    D F

    NnE E kT

    =+

    ( ):

    11 exp[( ) ]2

    AA

    F A

    NnE E kT

    =+

    :

    D A D AN N n n p p = + , ( ) :

    D AN N n p = :

    exp[( ) / ] exp[( ) / ] 0V V F C F C D AN E E kT N E E kT N N + =

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    2 exp( / )[exp( / )] exp( / ) 0exp( / ) exp( / )

    V VD AF F

    C C C C

    N E kTN NE kT E kTN E kT N E kT

    = :

    1

    1( )1 3 2( ) ln sinh2 4 exp( / )

    F i

    D ApF V C

    n C V G

    E

    N NmkTE E E kTm N N E kT

    = + + +

    Fermi :

    1sinh2

    D AF Fi

    i

    N NE E kTn

    = +

    1 2sinh ln( 1)x x x = + +

    10 sinhD AA N N x x

    2D A

    F Fi Fii

    N NE E kT En= +

    1sinh ln 2D A iA N N n x x

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    ln D AF Fii

    N NE E kT

    n=

    : n-type : p-type Fermi :

    Fermi n

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    Fermi p

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    2 23( )16g

    e e NNkT = =11.7 :

    18 3( ) 22.5 10gNN meVcm

    =

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    :

    2( ) /P P

    dp xJ qD A mdx

    = p(x) q

    .

    n(x) :

    2( ) /n ndn xJ qD A m

    dx=

    V(x)

    :

    2( )( ) /P Pdp xJ q p x E qD A m

    dx=

    2( )( ) /n n ndn xJ q n x E qD A m

    dx= +

    Einstein:

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    11600nP

    Tn

    DD TV = = = . ,

    ,

    .

    .

    ,

    , .

    .

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    Jp=0 :

    2( )0 ( ) /Pdp xq p x E qD A m

    dx=

    Einstein

    :

    ( ) ( ) /( )TVdV x dp xE V m

    dx p x dx= =

    :

    121 2 1

    2

    ( )( ) lnT Tpdp xdV x V V V V V

    dx p= = =

    ( )1 2 21exp / Tp p V V = ( Boltzmann)

    V21 1 2

    , x2-x1.

    :

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    ( )1 2 21exp / Tn n V V=

    1 1 2 2n p n p= np x.

    .

    .

    (NA ND ).

    :

    2

    1 0 2 0i

    p A nD

    np p N p pN

    = = = =

  • 26

    :

    Millman J. & Halkias C. Integrated Electronics. Analog and Digital

    Circuits and Systems. McGraw Hill (1972).

    Millman J. & Grabel A. , 2 , ,

    , (1996).

    . . & . .

    , (1980).

    Pierret, R. F. Semiconductor Device Fundamentals, Addison-Wesley ,

    International Edition (1996).

    012

    2 0

    ln ln lnp A DT T Tn i

    pp N NV V V Vp p n

    = = =