L08_5340_Sp11x

agreementkittensΗμιαγωγοί

1 Νοε 2013 (πριν από 3 χρόνια και 7 μήνες)

215 εμφανίσεις

EE 5340

Semiconductor Device Theory

Lecture 08


Spring 2011

Professor Ronald L. Carter

ronc@uta.edu

http://www.uta.edu/ronc

©rlc L08
-
15Feb2011

2

Second Assignment


Submit a signed copy of the document
posted at


www.uta.edu/ee/COE%20Ethics%20Statement%20Fall%2007.pdf



©rlc L08
-
15Feb2011

3

Test 1


Tuesday 22Feb11


11 AM Room 129 ERB


Covering Lectures 1 through 9


Open book
-

1 legal text or ref., only.


You may write notes in your book.


Calculator allowed


A cover sheet will be included with
full instructions. For examples see
http://www.uta.edu/ronc/5340/tests/.


©rlc L08
-
15Feb2011

4

Diffused or Implanted

IC Resistor (Fig 2.45
1
)

©rlc L08
-
15Feb2011

5

An IC Resistor with

L = 8W

(M&K)
1

©rlc L08
-
15Feb2011

6

Typical IC doping

profile (M&K Fig. 2.44
1
)

©rlc L08
-
15Feb2011

7

Mobilities**

©rlc L08
-
15Feb2011

8

IC Resistor

Conductance

©rlc L08
-
15Feb2011

9

An IC Resistor with

N
s

= 8, R = 8R
s
(M&K)
1

©rlc L08
-
15Feb2011

10

The effect of lateral

diffusion (M&K
1
)

©rlc L08
-
15Feb2011

11

A serpentine pattern

IC Resistor (M&K
1
)

R = N
S
R
S

+ 0.65

N
C
R
S

note: R
C

= 0.65

R
S

©rlc L08
-
15Feb2011

12


The equilibrium carrier concentration
ahd the Fermi energy are related as




The potential







f

=
E
f
-
E
fi
)/q


If not in equilibrium,




a quasi
-
Fermi level




(imref) is used

Fermi Energy

©rlc L08
-
15Feb2011

13

Electron quasi
-
Fermi

Energy (n = n
o

+

n)

©rlc L08
-
15Feb2011

14

Hole quasi
-
Fermi

Energy (p = p
o

+

p)

©rlc L08
-
15Feb2011

15

E
x
-
field when

E
f

-

E
fi

not constant


Since
f

㴠(E
f
-

E
fi
)/q = V
t
ln(n
o
/n
i
)


When E
f

-

E
fi

= is position dependent,


E
x
=
-
d
f
/d‽
-
[d(E
f
-
E
fi
)/dx]



=
-

V
t

d[ln(n
o
/n
i
)]/dx


If non
-
equilibrium






f
n

= (E
fn
-
E
fi
)/q = V
t
ln(n/n
i
), etc


E
xn
=
-
[d
f
n
/dx] =
-
V
t
d[ln(n/n
i
)]/dx

©rlc L08
-
15Feb2011

16

Si and Al and model

(approx. to scale)

q
f
m,Al
~
4.1 eV

E
o

E
Fm

E
Fp

E
Fn

E
o

E
c

E
v

E
Fi

q
f
s,n

q
c
si
~
4.05

eV

E
o

E
c

E
v

E
Fi

q
f
s,p

metal

n
-
type s/c

p
-
type s/c

q
c
si
~
4.05

eV

©rlc L08
-
15Feb2011

17

Making contact be
-

tween metal & s/c


Equate the E
F

in
the metal and s/c
materials far from
the junction


E
o
(the free level),
must be continuous
across the jctn.

N.B.: q
c

=4⸰5敖e(Si),

and q
f

=ⁱ
c


E
c

-

E
F

E
o

E
c

E
F

E
Fi

E
v

q
c

(electron
affinity)

q
f
F

q
f

(work function)

©rlc L08
-
15Feb2011

18

Equilibrium Boundary
Conditions w/ contact


No discontinuity in the free level, E
o

at
the metal/semiconductor interface.


E
F,metal

= E
F,semiconductor

to bring the
electron populations in the metal and
semiconductor to thermal equilibrium.


E
o

-

E
C

= q
c
semiconductor

in all of the s/c.


E
o

-

E
F,metal

= q
f
metal

throughout metal.

©rlc L08
-
15Feb2011

19

Ideal metal to n
-
type

barrier diode
(
f
m
>
f
s
,V
a
=0)

E
Fn

E
o

E
c

E
v

E
Fi

q
f
s,n

q
c
s

n
-
type s/c

q
f
m

E
Fm

metal

q
f
Bn

q
f
i

q
f

n

No disc in
E
o

E
x
=0 in metal
==>
E
o
flat

f
Bn
=
f
m
-

c
s

=
elec

mtl

to
s/c
barr

f
i
=
f
Bn
-
f
n
=
f
m
-
f
s

elect s/c to
mtl

barr


Depl reg

©rlc L08
-
15Feb2011

20

Metal to n
-
type

non
-
rect cont (
f
m
<
f
s
)

E
Fn

E
o

E
c

E
v

E
Fi

q
f
s,n

q
c
s

n
-
type s/c

q
f
m

E
Fm

metal

q
f
B,n

q
f
n

No disc in E
o

E
x
=0 in metal
==> E
o

flat

f
B,n
=
f
m
-

c
s
= elec mtl to
s/c barr

f
i
=
f
Bn
-
f
n
< 0

Accumulation
region

Acc reg

q
f
i

©rlc L08
-
15Feb2011

21

Ideal metal to p
-
type

barrier diode (
f
m
<
f
s
)

No disc in
E
o

E
x
=0 in metal ==>
E
o
flat

f
Bn
=
f
m
-

c
s

=
elec

mtl

to s/c
barr
.

f
Bp
=
f
m
-

(
c
s

+
E
g
)
=
hole m to
s
barr
.

f
i

=
f
m
-
f
s,p

= hole
s/c to
mtl

barr
.

E
Fp

E
o

E
c

E
v

E
Fi

q
f
s,p

q
c
s

p
-
type s/c

q
f
m

E
Fm

metal

q
f
Bn

q
f
i

q
f
p
<0

Depl reg

q
f
Bp

q
f
i

©rlc L08
-
15Feb2011

22

Metal to p
-
type

non
-
rect cont (
f
m
>
f
s
)

No disc in
E
o

E
x
=0 in metal ==>
E
o

flat

f
B,n

=
f
m

-

c
s

=
elec

mtl

to s/c
barr

f
Bp
=
f
m
-

(
c
s

+
E
g
)
=
hole m to s

f
i

=
f
m
-
f
s,n

= s/c
to
mtl

barr
.

E
Fi

E
o

E
c

E
v

E
fP

q
f
s,n

q
c
s

n
-
type s/c

q
f
m

E
Fm

metal

q
f
Bn

q(
f
i
)

q
f
p

Accum reg

q
f
Bp

q
f
i

©rlc L08
-
15Feb2011

23

Metal/semiconductor

system types


n
-
type semiconductor


Schottky diode
-

blocking for
f
m

>
f
s


contact
-

conducting for
f
m

<
f
s


p
-
type semiconductor


contact
-

conducting for
f
m

>
f
s


Schottky diode
-

blocking for
f
m

<
f
s



©rlc L08
-
15Feb2011

24

References

1 and
M&K
Device

Electronics for Integrated
Circuits
, 2 ed., by Muller and
Kamins
, Wiley,
New York, 1986. See
Semiconductor Device
Fundamentals
, by
Pierret
, Addison
-
Wesley,
1996, for another treatment of the


model.

2
Physics of Semiconductor Devices
, by S. M.
Sze
,
Wiley, New York, 1981.

3 and **
Semiconductor Physics & Devices
, 2nd ed.,
by
Neamen
, Irwin, Chicago, 1997.

Fundamentals of Semiconductor Theory and
Device Physics
, by
Shyh

Wang, Prentice Hall,
1989.