Solutions Manual to Accompany
SEMICONDUCTOR DEVICES
Physics and Technology
2nd Edition
S. M. SZE
UMC Chair Professor
National Chiao Tung University
National Nano Device Laboratories
Hsinchu, Taiwan
New York. Chicester / Weinheim / Brisband / Singapore / Toronto
John Wiley and Sons, Inc
1
Contents
Ch.1   Introduction---------------------------------------------------------------------  0
Ch.2   Energy Bands and Carrier Concentration --------------------------------------  1
Ch.3   Carrier Transport Phenomena --------------------------------------------------  7
Ch.4   p-n Junction -------------------------------------------------------------------- 16
Ch.5   Bipolar Transistor and Related Devices---------------------------------------- 32
Ch.6   MOSFET and Related Devices------------------------------------------------- 48
Ch.7   MESFET and Related Devices ------------------------------------------------- 60
Ch.8   Microwave Diode, Quantum-Effect and Hot-Electron Devices --------------- 68
Ch.9  Photonic Devices ------------------------------------------------------------- 73
Ch.10  Crystal Growth and Epitaxy--------------------------------------------------- 83
Ch.11  Film Formation---------------------------------------------------------------- 92
Ch.12  Lithography and Etching ------------------------------------------------------ 99
Ch.13  Impurity Doping--------------------------------------------------------------- 105
Ch.14  Integrated Devices------------------------------------------------------------- 113
0
CHAPTER 2
1.  (a)  From  Fig.  11a,  the  atom  at  the  center  of  the  cube  is  surround  by  four
equidistant nearest neighbors that lie at the corners of a tetrahedron.  Therefore
the distance between nearest neighbors in silicon (a = 5.43 Å) is
1/2 [(a/2)2 + (
a2 /2)2]1/2  = 
a3 /4  =  2.35 Å.
(b) For the (100) plane, there are two atoms (one central atom and 4 corner atoms
each contributing 1/4 of an atom for a total of two atoms as shown in Fig. 4a)
for an area of a2, therefore we have
  2/ a2 = 2/ (5.43 × 10-8)2  = 6.78 × 1014 atoms / cm2
Similarly we have for (110) plane (Fig. 4a and Fig. 6)
a2 2  = 9.6 × 1015 atoms / cm2,
(2 + 2 ×1/2 + 4 ×1/4) /
and for (111) plane (Fig. 4a and Fig. 6)
(3 × 1/2 + 3 × 1/6) / 1/2(
a2 )(
a
) = 
3
2
2
3
2
a
2
 = 7.83 × 1014 atoms / cm2.
2.  The heights at X, Y, and Z point are 
3
,4
3 .
1 and 4
,4
3.  (a) For the simple cubic, a unit cell contains 1/8 of a sphere at each of the eight
      corners for a total of one sphere.
4 Maximum fraction of cell filled
= no. of sphere × volume of each sphere / unit cell volume
= 1 × 4(a/2)3 / a3  = 52 %
(b) For a face-centered cubic, a unit cell contains 1/8  of  a  sphere  at  each  of  the
eight corners for a total of one sphere.  The  fcc also contains half a sphere at
each of the six faces for a total of three spheres.  The nearest neighbor distance
is 1/2(a 2 ).  Therefore the radius of each sphere is 1/4 (a 2 ).
4 Maximum fraction of cell filled
= (1 + 3) {4[(a/2) / 4 ]3 / 3} / a3  = 74 %.
(c) For a diamond lattice, a unit cell contains 1/8 of a sphere at each of the eight
corners for a total of one sphere, 1/2 of a sphere at each of the six faces for a
total  of  three  spheres,  and  4  spheres  inside  the  cell.    The  diagonal  distance
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4 cosŁ = 
Ł= cos-1 (
1-
3
1-
3
) = 109.470 .
between (1/2, 0, 0) and (1/4, 1/4, 1/4) shown in Fig. 9a is
  D = 
1
2
a
2
2
+
a
2
2
+
a
2
2
 = 
a
4
3
The radius of the sphere is D/2 = 
a
8
4 Maximum fraction of cell filled
3
= (1 + 3 + 4)
 ap
4
8
3
3
3
/ a3  =  3 / 16  = 34 %.
This is a relatively low percentage compared to other lattice structures.
1d  = 
2d  = 
4.   
    
    
    
3d  = 
1d + 2d + 3d + 4d = 0
1d • ( 1d + 2d + 3d + 4d ) = 
1d + 1d •
2d + 1d • 3d + 
2
4d  = d
1d • 0 = 0
4d = 0
1d •
4d2+ d2 cosŁ12 + d2cosŁ13 + d2cosŁ14 = d2 +3 d2 cosŁ= 0
5.  Taking  the  reciprocals  of  these  intercepts  we  get  1/2,  1/3  and  1/4.    The  smallest
three  integers  having  the  same  ratio  are  6,  4,  and  3.    The  plane  is  referred  to  as
(643) plane.
6.  (a) The lattice constant for  GaAs is 5.65 Å, and the atomic weights of  Ga and As
are  69.72  and  74.92  g/mole,  respectively.    There  are  four  gallium  atoms  and
four arsenic atoms per unit cell, therefore
4/a3 = 4/ (5.65 × 10-8)3  =  2.22 × 1022 Ga or As atoms/cm2,
Density = (no. of atoms/cm3 × atomic weight) / Avogadro constant
       = 2.22 × 1022(69.72 + 74.92) / 6.02 × 1023 = 5.33 g / cm3.
(b) If  GaAs  is  doped  with  Sn  and  Sn  atoms  displace  Ga  atoms,  donors  are
formed, because Sn has four valence electrons while  Ga has only three.  The
resulting semiconductor is n-type.
7.   (a) The melting temperature for Si is 1412 ºC, and for SiO 2 is 1600 ºC.  Therefore,
SiO2  has  higher  melting  temperature.  It  is  more  difficult  to  break  the  Si-O
bond than the Si-Si bond.
 (b) The seed crystal is used to  initiated  the  growth  of  the  ingot  with  the  correct
crystal orientation.
 (c) The crystal orientation determines the semiconductor’s chemical and electrical
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properties, such as the etch rate, trap density, breakage plane etc.
(d)  The temperating of the crusible and the pull rate.
8.   Eg (T) = 1.17 – 
    \
4.73x10
+
T
(
4
T
636)
2
 for  Si
 Eg ( 100 K) = 1.163 eV , and Eg (600 K) = 1.032 eV
 Eg(T) = 1.519 –
 \ Eg( 100 K) = 1.501 eV, and Eg (600 K) = 1.277 eV .
 for GaAs
T
(
+
5.405x10
2
4
T
204)
9. 
The  density  of  holes  in  the  valence  band  is  given  by  integrating  the  product
N(E)[1-F(E)]dE  from  top  of  the  valence  band  (
VE   taken  to  be  E  =  0)  to  the
bottom of the valence band Ebottom:
bottom
{
/1 
where 1 –F(E) = 
1
If EF – E >> kT then
N(E)[1 – F(E)]dE                     (1)
+
(e1
[
(
E F
Then from Appendix H and , Eqs. 1 and 2 we obtain
] 1
]kT
)
                       (2)
1 – F(E) ~ exp
 = [
FEE -
[
EE
E
kT
e
/)
F
(
+
1 
E 
p = 
}/kT
]
)
0 
p = 4[2mp / h2]3/2 
E 
bottom
0 
E1/2 exp [-(EF – E) / kT ]dE      (3)
Let x a E / kT , and let Ebottom = 
, Eq. 3 becomes
 x1/2exdx
where the integral on the right is of the standard form and equals  p  / 2.
p = 4(2mp / h2)3/2 (kT)3/2 exp [-(EF / kT)]
0 
- 
4  p = 2[2mp kT / h2]3/2 exp [-(EF / kT)]
By referring to the top of the valence band as EV instead of E = 0 we have,
p = 2(2mp kT / h2)3/2 exp [-(EF – EV) / kT ]
or 
where     NV = 2 (2mp kT / h2)3 .
p = NV exp [-(EF –EV) / kT ]
10.  From Eq. 18
NV  = 2(2mp kT / h2)3/2
The effective mass of holes in Si is
     mp = (NV / 2) 2/3 ( h2 / 2kT )
(
.
625
6
(
p
.
3812
34
2
)
)(
300
)
10
10
23
       = 
66.2
19
10
6
m10
3
2
3
2
       = 9.4 × 10-31 kg = 1.03 m0.
Similarly, we have for GaAs
     mp = 3.9 × 10-31 kg = 0.43 m0.
11.  Using Eq. 19
3
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-
-
-
-
-
-
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-
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·
·
-
-
-
·
·
=
(
E
C
+
Ei
E
V
2)
(
kT
+
)
 ln2
(
NN
V
C
)
= (EC+ EV)/ 2 + (3kT / 4) ln 
(
p mm
n
)6)(
2
3
                     (1)
At 77 K
        Ei = (1.16/2) + (3 × 1.38 × 10-23T) / (4 × 1.6 × 10-19) ln(1.0/0.62)
          = 0.58 + 3.29 × 10-5 T = 0.58 + 2.54 × 10-3 = 0.583 eV.
       Ei = (1.12/2) + (3.29 × 10-5)(300) = 0.56 + 0.009 = 0.569 eV.
At 300 K
At 373 K
       Ei = (1.09/2) + (3.29 × 10-5)(373) = 0.545 + 0.012 = 0.557 eV.
Because  the  second  term  on  the  right-hand  side  of  the  Eq.1  is  much  smaller
compared to the first term, over the above temperature range, it is reasonable to
assume that Ei is in the center of the forbidden gap.
12.  KE  = 
(
E
 
top
 
E
C
)
EE
C
EE
C
e
(
EE
F
)
kT
/
d
E
E
 
top
 
E
C
eEE
C
(
EE
F
/)
kT
d
E
x
(
EE
)
C
  = kT 
5
2
3
2
 = kT
3
1
x
x
2
x
de
x
2
x
de
x
 
0 
 
0 
       = 
3
2
kT
.
 = kT
.
.
5051
.
50
p
p
13.  (a) p = mv = 9.109 × 10-31 ×105 = 9.109 × 10-26  kg–m/s
  l  = 
h
p
(b) 
nl =
 = 
.
6
626
.
109
9
m0
pm
l
 = 
34
26
10
10
1
063
.
0
= 7.27 × 10-9 m = 72.7 Å
× 72.7 = 1154 Å .
14.  From Fig. 22 when ni = 1015 cm-3, the corresponding temperature is 1000 /  T = 1.8.
So that T = 1000/1.8 = 555 K or 282  .
15.  From         Ec – EF = kT ln [NC / (ND – NA)]
which can be rewritten as      ND – NA = NC exp [–(EC – EF) / kT ]
Then            ND – NA = 2.86 × 1019 exp(–0.20 / 0.0259) = 1.26 × 1016 cm-3
 or              ND= 1.26 × 1016 + NA = 2.26 × 1016 cm-3
A  compensated  semiconductor  can  be  fabricated  to  provide  a  specific  Fermi
energy level.
16.  From Fig. 28a we can draw the following energy-band diagrams:
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17. 
(a)  The  ionization  energy  for  boron  in  Si  is  0.045  eV.    At  300  K,  all  boron
impurities are ionized.  Thus  pp = NA = 1015 cm-3
np = ni
2 / nA = (9.65 × 109)2 / 1015 = 9.3 × 104 cm-3.
The Fermi level measured from the top of the valence band is given by:
EF – EV = kT ln(N V/ND) = 0.0259 ln (2.66 × 1019 / 1015) = 0.26 eV
(b) The boron atoms compensate the arsenic atoms; we have
pp = NA – ND = 3 × 1016 – 2.9 × 1016 = 1015 cm-3
Since pp is the same as given in (a), the values for np and EF are the same as
in  (a).    However,  the  mobilities and  resistivities  for  these  two  samples  are
different.
18.  Since ND >> ni, we can approximate n0 = ND and
p0 = ni
2 / n0 = 9.3 ×1019 / 1017 = 9.3 × 102 cm-3
From n0 = ni exp
E
F
E
i
kT
,
we have
EF – Ei = kT ln (n0 / ni) = 0.0259 ln (1017 / 9.65 × 109) = 0.42 eV
The resulting flat band diagram is :
5
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19. Assuming  complete  ionization,  the  Fermi  level  measured  from  the  intrinsic
Fermi level is 0.35 eV for 1015 cm-3, 0.45 eV for 1017 cm-3, and 0.54 eV for 1019
cm-3.
The number of electrons that are ionized is given by
 ]
 ND[1 – F(ED)] = ND / [1 + e
n  @
Tk
E
E
(
)
D
/
F
Using the Fermi levels given above, we obtain the number of ionized donors as
n = 1015 cm-3                              for ND = 1015 cm-3
n = 0.93 × 1017 cm-3                    for ND = 1017 cm-3
n = 0.27 × 1019 cm-3                    for ND = 1019 cm-3
Therefore,  the  assumption  of  complete  ionization  is  valid  only  for  the  case  of
1015 cm-3.
16
16
E
10
E
(
 = 
10
-+
-+
e
e1
 = 5.33 × 1015 cm-3
kT
/)
D
F
0
.
135
20.  ND
      = 
1
+ = 
1
1016
1
+
145
.
1
 The neutral donor = 1016 – 5.33 ×1015 cm-3  = 4.67 × 1015 cm-3
 4 The ratio of  
N O
D
+
N
D
 =   
.
764
.
335
= 0.876 .
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