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Lecture slides on the book solid state electronics device by Ben G Streetman
Typology: Slides
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Prof. Min-Koo Han
010-5225-
Class Hour : Monday 9:00 – 11:45 AM
Class Room : 이이이 #
Office : Room #114 at 이이이
Text : Solid State Electronic Devices(7th
Edition)
Ben G. Streetman
*** For Si,**
N
C
=2.75x
19
cm
-
N
V
=1.30x
19
cm
-
N
C
=4.33x
17
cm
N
V
=8.05x
18
cm
Current characteristic versus time during
diode switching
p
+
n Junction
p
p
p
x
J
t e
p
1
Integration from 0 to
0
p
p p
0
Q ( t ) eA pdx
p
p
p
p
p
When t=0, I
r
=
at x=
x 0
n
p (t)
p
f p
p
s
Q s
n no a t
t
p f p
p
p f p
p
p
sQ s I
Q s
Metal-Semiconductor Contact ; before contact
Work Function -
Electron Affinity -
M S
,
Vacuum Level
Ideal Metal-Semiconductor Contact ( I )
M S
Rectifying Contact
- Schottky Diode
Φ
B
= Φ
M
Schottky model
(1931)
Current Flow in Schottky Diode
Forward Bias Reverse Bias
( 1 )
**/ /
k T q V k T
D
B A
I A A T e e
B
dominant
I
R-G
negligible
M n-Si
The Schottky Barrier Diode
Qualitative Characteristics
(a) Idealized equilibrium band
diagram (energy versus distance)
for a metal semiconductor
rectifying contact
(Schottky barrier).
(b) Charge at an idealized metal-
semiconductor junction.
The negative charge is
approximately a delta function at
the metal surface.
The positive charge consists
entirely of ionized donors (here
assumed constant in space) in
the depletion approximation.
(c) Field at an idealized metal-
semiconductor junction.
Qualitative Characteristics
Small signal capacitance
sin(wt)
V
R
M
S
- Q
+ Q
2 ( )
'
bi R
s d
R
n
d
V V
eN
dV
dx
C eN
s d
bi R
eN
2
slope=2/(eε
s
N
d
)
Bn bi n
Ideal Junction Properties
R
dV
d Q
C
1 2
2 ( ) 1
/
d a d
s bi R a
n
N N N
N
e
ε V V
x
R
n
d
R
dV
dx
eN
dV
d Q
C
1 2
2 ( )( )
/
bi R a d
s a d
V V N N
eε N N
C
In the case of PN
In the same way with PN
Ideal Junction Properties
Nonideal effects on the Barrier Height
eE
x
e
s
2
2
x
e
x
x
e
x
x
e
x E x dx
s
s
s
potentialenergyof electron:-e ( )
2
Ex
x
e
x
s
Barrier lowering
position of maximum barrier, x
m
s s
m
eE
e
x
Electric field in
dielectric
0
( ( ))
dx
d e x
Nonideal effects on the Barrier Height
