Semiconductors
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Transcript of Semiconductors
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Si: 0.543 nm
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sp3 , r. ,
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Si , Ge GaAs
Si: , EG= 1.12 eV
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Ge : L , EG= 0.67 eV
GaAs : EG= 1.43eV
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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
( ) .
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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 =
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( ) ( )t o p
C
E
C C bE
f E g E d E N n = =
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:
[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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11
:
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
= = = =
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:
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
= = =