Solutions Manual Exercise Solutions Chapter 1Exercise ProblemsEX1. For a body-centered cubic, 2 atoms per unit cell. ThenVolume Density == 22 −a 3 o b475 10. x 8 g 3Or Volume Density = 187 10./ xa 22 tomscm 3####### ____EX1.For a (132) →→FH 111 IK HF 6 KI66 26 pqs 3,, ,,So that pq s ===623,,####### ...
An Introduction to Semiconductor Devices Chapter 1 Solutions Manual Exercise Solutions ______________________________________________________________________________________
Chapter 1 Exercise Problems
(b) Also (113) plane ⇒
FH
EX1.1 For a body-centered cubic, 2 atoms per unit cell. Then 2
Volume Density =
3
=
ao
b
2
4 .75 x10
−8
Intercepts of plane are p = 3 , q = 3 , s = 1 _______________________________________
g
3
Or 22
Volume Density = 187 . x10 atoms / cm
Test Your Understanding Exercises
3
____________________________________ EX1.2 For a (132) →
F H
1
I F K H
1 1 , → p q s ,
IK
1 1 1 → ( 3, 3, 1) , , 1 1 3
6 6 6 , , 6 2 3
TYU1.1 Body-centered cubic = 2 atoms per unit cell. 2 Density = 3 ao
IK
So that p = 6, q = 2, s = 3
____________________________________
Then a o = 3.42 A Now
EX1.3 (a) For a body-centered cubic, (100) plane, effectively 1 atom per plane. Then Surface Density =
1 atom 2
=
ao
b
1
4.75 x10
−8
g
14
=
(a ) o
c h b ao
2
=
−8
4. 75x 10
g
2
(3.42 ) 3 4
r = 1.48 A
°
2
____________________________________ TYU1.2
d=
2
ao 2
(4.83) 2 4
°
⇒ d = 3.42 A
TYU1.3
2
Surface Density = 6.27 x 10 atoms / cm
=
____________________________________
Or 14
5 x10
or
2
2
−23
= 4 x10
22
°
4 r = ao 3 ⇒ r =
Or Surface Density = 4 .43 x10 atoms / cm (b) (110) plane, effectively 2 atoms per plane. Then Surface Density 2 atoms
2
3
⇒ ao =
Density =
2
8 3
ao
____________________________________
=
8
b5.43x10 g −8
3
Or Density = 5x 10 22 cm −3
EX1.4 (a) For p = 1 , q = 1 , s = 3 ; then [113] direction
____________________________________
1
An Introduction to Semiconductor Devices Chapter 1 Solutions Manual Problem Solutions ______________________________________________________________________________________
Chapter 1 Problem Solutions
(b) Face-centered cubic lattice d d = 4r = a 2 ⇒ a = =2 2 r 2
1.1 (a) fcc: 8 corner atoms × 1/8 = 1 atom 6 face atoms × ½ = 3 atoms Total of 4 atoms per unit cell
h = 16 2 r F 4 πr IJ 4 atoms per cell, so atom vol. = 4G H 3K Then
Ratio =
−8
g
3
⇒
Density of Ga = 2.22 x10
22
Unit cell vol. = a cm
F 4 rI = H3K
3
FG 4πr IJ H3K 3
Then
Density of As = 2.22 x10 cm _______________________________________
FG 4π r IJ H 3 K × 100% ⇒ Ratio = F 4r I H 3K 3
2
1.3
3
8 Ge atoms per unit cell 8 Density = ⇒ 8 3 5.65x10−
g
22
3
2 atoms per cell, so atom vol. = 2
−3
22
Ratio = 74%
−3
4 As atoms per unit cell, so that
b
3
16 2 r (c) Body-centered cubic lattice 4 d = 4r = a 3 ⇒ a = r 3
4 Ga atoms per unit cell 5.65 x10
FG 4πr IJ H 3 K ×100% ⇒
4
1.2
b
Ratio = 68%
(d) Diamond lattice −3
Density of Ge = 4.44 x10 cm _______________________________________
Body diagonal = d = 8r = a 3 ⇒ a =
1.4 (a) Simple cubic lattice; a = 2 r
Unit cell vol. = a 3 =
F 8r I H 3K
FG 4πr IJ H3K 3
FG 4 πr IJ H3K 3
Then
FG 4πr IJ H 3 K × 100% ⇒ Ratio = 34% Ratio = F 8r I H 3K 3
Then
8
3
3
r
3
8 atoms per cell, so atom vol. 8
1 atom per cell, so atom vol. = (1)
8r
8 3
3
Unit cell vol = a3 = (2 r) = 8 r3
FG 4 πr IJ H 3 K × 100% ⇒ Ratio =
3
3
(c) Diamond: 8 corner atoms × 1/8 = 1 atom 6 face atoms × ½ = 3 atoms 4 enclosed atoms = 4 atoms Total of 8 atoms per unit cell _______________________________________
4
3
3
(b) bcc: 8 corner atoms × 1/8 = 1 atom 1 enclosed atom = 1 atom Total of 2 atoms per unit cell
Density =
c
3
Unit cell vol = a = 2 2 r
3
Ratio = 52.4%
_______________________________________
2
An Introduction to Semiconductor Devices Chapter 1 Solutions Manual Problem Solutions ______________________________________________________________________________________
B-type: 1 atom per unit cell, so . x10 23 cm −3 Density (b) = 118 _______________________________________
1.5 We have 8r = a o 3 so that
r=
5.65 3 8
= 1.223 A
1.9
°
Simple cubic; a o = 2 r = 4.2 A
Then °
d = 2 r = 2.45 A _______________________________________
bcc: 4r = a o
1.6 From Problem 1.4, percent volume of fcc atoms is 74%. Therefore after coffee is ground,
fcc: 4 r = ao 2 ⇒ ao =
3
8
From 1.3d, a =
(5.43) 3
°
= 5.94 A
2 8(2.1) 3 °
1.10 (b) ° . + 1.0 ⇒ a = 2.8 A a = 18
r °
. A = 118 8 8 Center of one silicon atom to center of nearest ° neighbor = 2r ⇒ 2.36 A
(c)
(b) Number density 8 22 −3 = ⇒ Density = 5x10 cm 3 −8 5.43x10
Cl: Density (same as Na) = 2.28 x10 cm
so that r =
b
=
Na: Density =
= ρ=
N ( At. Wt.)
b5 x10 g(28.09) ⇒ 23
NA
6. 02 x 10
ρ = 2.33 grams / cm 3 _______________________________________
ρ=
1.8 °
(a) a = 2r A = 2( 1.02) = 2.04 A Now
−3
−3
4.85x 10
− 23
b 2.8x10 g −8
3
⇒
_______________________________________ 1.11
so that rB = 0.747 A ° (b) A-type; 1 atom per unit cell 1 Density = ⇒ 8 3 2.04 x10 −
. )= 8 A (a) a 3 = 2 (2.2 ) + 2 (18 so that ° a = 4.62 A
g
23
3
ρ = 2.21 gm / cm3
2rA + 2rB = a 3 ⇒ 2rB = 2.04 3 − 2.04
b
22
= 2.28 x10 cm
b2.8 x10 g −8
(d) Na: At.Wt. = 22.99 Cl: At. Wt. = 35.45 So, mass per unit cell 1 1 (22.99 )+ (35. 45) − 23 2 = 4.85 x10 = 2 6.02 x10 23 Then mass density is
22
=
12
22
g
(c) Mass density
°
a o = 9.70 A _______________________________________
3
a 3
3 4( 2.1)
= 4.85 A
or
1.7 °
4(2.1)
diamond: 8r = a o 3 ⇒ a o =
Volume = 0.74 cm _______________________________________
(a) a = 5.43 A
3 ⇒ ao =
°
−3
. x10 cm Density(A) = 118
Density of A =
1
b4.62 x10 g −8
3
3
°
⇒ 1.01x1022 cm −3
An Introduction to Semiconductor Devices Chapter 1 Solutions Manual Problem Solutions ______________________________________________________________________________________
Density of B =
1
b4.62 x10 g
22
⇒ 1.01x10 cm
−8
1.15 (a) Planes intercept at: (i) p = 1, q = ∞ , s = ∞ (ii) p = 3, q = 1, s = ∞ (iii) p = 3, q = ∞ , s = 2
−3
(b) Same as (a) (c) Same material _______________________________________ 1.12 (a) Surface density 1 1 = 2 = 8 a 2 4.62 x10 −
b
3 .31 x10
14
g
(b) Vector components: (i) p = 1, q = 1, s = 0 (ii) p = 3, q = 1, s = 1 (iii) p = 1, q = 2 , s = 3 _______________________________________
⇒
2
2
−2
cm
1.16 (a)
Same for A atoms and B atoms (b) Same as (a) (c) Same material _______________________________________
(b)
1.13
1
(a) Vol density =
a3o
F 1 , 1 , 1I ⇒ (313) H 1 3 1K F 1 , 1 , 1I ⇒(121) H 4 2 4K
_______________________________________ 1
Surface density =
2
ao
1.17
2
°
(a) d = ao = 5.25 A
(b) Same as (a) _______________________________________
(b) d =
ao
No . atoms
2
b5. 43x10 g −8
2
(110) plane: Density =
b5. 43x 10 g
2
(111) plane: Density =
1.18 ° (a) d = a o = 5.20 A
No . atoms 2
2
(b) d = 14
= 9.59 x10 cm No . atoms 2
ao
=
3
(5.20) 2 2
= 3.68 A°
(5.20 ) 3
= 3. 00 A ° 3 3 _______________________________________
c 3 2h
14
2
2
(c) d =
a1 6f ⋅ 3 + a1 2f ⋅ 3 = 7.83x10 b5. 43x 10 g c 3 2h −8
ao 2
−2
2
ao
=
°
−2
14
4
−8
d=
= 6. 78 x10 cm
ao
=
ao 3
= 3.03 A 3 _______________________________________ (c)
2
ao =
°
= 3.71 A
2
1.14
(100) plane: Density =
2
=
1.19 cm
−2
ao =
4r
=
4(2.25 )
3 3 (a) Density = 2 2 = 3 ao 5.196 x10− 8
(a) (110) = highest density (b) (100) = lowest density _______________________________________
b
4
g
. A = 5196
3
°
= 1.43 x10 22 cm −3
An Introduction to Semiconductor Devices Chapter 1 Solutions Manual Problem Solutions ______________________________________________________________________________________
(b) d =
ao
2
=
5196 2 .
2 2 (d) Surface density 2 2 = 2 = −8 ao 2 . x10 5196
b
1.23
= 3.67 A
FH θ IK = a 4 = 2 ca 3 h 4
°
We find
o
g
1 3
so that
θ
2
2
2
or 14
o
cos
= 54.74°
or
−2
= 5.24 x 10 cm _______________________________________
θ = 109.5° _______________________________________
1.20
1.24
22 −3 Density of silicon atoms = 5x10 cm and 4 valence electrons per atom, so 23
(a) Ratio =
−3
Density of valence electrons = 2 x10 cm _______________________________________
(b) Ratio =
5x10 22 2 x1015 22
−5
⇒ 8x 10 % −6
⇒ 4 x10 %
5x10 _______________________________________
1.21 Density of GaAs atoms 8 atoms 22 −3 = = 4.44 x10 cm 8 3 5.65x10 −
b
4 x10 16
1.25
b5 x10 g(30 .98 ) ⇒ (a) Fraction by weight ≈ b5 x10 g(28.06 )
g
16
22
An average of 4 valence electrons per atom, −3 23 Density of valence electrons = 1.77 x 10 cm _______________________________________
. x10 −4 % 110
(b) Fraction by weight
b10 g(10.82 ) b 5x10 g( 30.98) +b 5 x10 g( 28.06) ⇒ 18
≈
1.22 Silver: Group 1 = 1 valence electron per atom 3 At.Wt. = 107.88, Mass density = 10.50 gm / cm Mass per unit cell, 107.88 −22 = = 1.79x 10 6. 02 x 1023 Now − 22
ρ=
1. 79x 10 a 3o
FG 1.79x10 JI H 10.50 K − 22
⇒ ao =
16
22
−4
7.71 x10 % _______________________________________
1.26 1
Volume density =
d
1 /3
3
15 −3 = 2x 10 cm
So −6
d = 7.94 x10 cm = 794 A
or
°
°
We have aO = 5.43 A So
°
ao = 2.57 A Then, density of valence electrons 1 = −8 2.57 x10 or
b
22
d 794 d = ⇒ = 146 ao 5.43 ao
g
3
_______________________________________
−3
Density = 5.89x 10 cm _______________________________________
5
An Introduction to Semiconductor Devices Chapter 2 Solutions Manual Exercise Solutions ______________________________________________________________________________________
Chapter 2 Exercise Problems EX2.1 (a)
E =
hc
λ
Then
b 6.625x10 gb 3x10 g b10 gx10 − 34
=
10
p
−19
1.99 x10
LM 1 − 1 PO a 4π ∈ f ⋅ 2( =) N( n + 1) n Q −b 9.11x10 gb 1.6x 10 g = 4 π b8 .85 x10 g (2 )b1.054 x10 g L 1 − 1 OP ×M (n + 1) n Q N We want L 1 − 1 PO ≤ 0.20 E − E = −13.58 M N(n + 1) n Q
− 19
− 19
1.6x 10
= 1.24 eV
− 34
− 16
J Then
= 1.24 x 10 3 eV 1.6x 10−19 ____________________________________
2
FH pIK m
1
2
=
m
2
b 3. 68x 10 g E= 2b 5x10 g − 26
− 31
p
n +1
− 19
(n + 1)
2
2
≥
1 n2
− 0 .0147
n=5 ____________________________________
2m
2
EX2.4 = 1.35 x10 −21 J
b gb1.6x10 g = 1.6x10
ΔE = 10
−8
− 19
− 27
J
so mv 1Δv = 1.6 x10 −27 −3
= 8.46x 10 eV
E = 20 meV = 3.2 x10 2 mE =
2
We find
2
or Δv =
p=
2
2
(b) and
4
− 34
n
1
− 21
1.6 x10
2
or
and 1. 35x10
−19
2
EX2.2 (a) 6. 625x 10 −34 h p= = = 3.68 x10 −26 kg − m / s 180x 10−10 λ Now 2
2
2
2
− 12
1.99 x10 −16
mv =
2
−31
10
−8
1
4
o
b6.625x10 gb3x10 g = 1. 99x 10 E= b10 x10 g E=
− mo e
En +1 − En =
(b)
E=
= 8.68 x10 −9 m
EX2.3
E=
so
7.636 x10
− 26
____________________________________
J
Then
E=
6. 625x 10
λ = 86.8 A°
or E = 1.99 x10
=
or
−8
4
− 34
h
λ=
b
−21
2 9.11x10
J −31
b
1. 6 x10−27
9.11x 10−31
gb
2 x 105
g
−3
= 8. 78 x10 m / s or
= 0.878 cm / s ____________________________________ Δv
gb3.2 x10 g −21
or 26
p = 7.636 x10 − kg − m / s
6
An Introduction to Semiconductor Devices Chapter 2 Solutions Manual Exercise Solutions ______________________________________________________________________________________ EX2.8 From Example 2.8, we can write
EX2.5 From Example 2.5 N=
4π ( 2 m)
=
h
3/ 2
⋅
3
b
2 3
⋅E
4π 2 9.11x10
b6.625x10 × b 3.2 x 10
−31
− 34
−19
F 1 I = 4.6kT H 0.01K
3 / 2 2 eV 1 eV
g F2I g H3K g − b1.6x10 g
E − E F = kT ln
3 /2
3 /2
−19
____________________________________ 3 /2
Test Your Understanding Exercises
or
TYU2.1
N = 8 .29 x10 27 m −3 = 8 .29 x10 21 cm−3 ____________________________________
EX2.6
(a)
(a)
L− a E − E f O MN kT PQ L −( 0. 3+ 0. 0259)O = exp NM 0.0259 QP F
f F = exp
f F = 3. 43x10
f F = exp
L MN
−7
1 − f F = 4.98 x10
(b)
LM −( 0.35 + 2 (0.0259 ))OP N 0.0259 Q
1 − f F = exp
−6
−( 0.3 + 2( 0.0259)) 0.0259
or
PQO
−7
1 − f F = 183 . x10 ____________________________________
or
TYU2.2
−6
f F = 1.26 x10 ____________________________________
fF = 1 + exp
EX2.7 f F = 0.005 = exp
or
LM −0.20 O N 0.0259 PQ
= ln (200 )
or kT =
0. 20
ln( 200) We can write
= 0.03775 eV
0.03775 = (0.0259 )
kT
KI
=
1 1 + exp( 4)
f F = 0.018 = 18% . ____________________________________
F +0.20I = 1 = 200 H kT K 0.005
kT
F H
1 E − EF
or
exp
Then +0.20
F
or
or (b)
LM −aE − E f PO N kT Q LM −(0.35 + 0.0259 ) OP = exp N 0.0259 Q
1 − f F ≅ exp
FTI H300 K
which yields T = 437 K ____________________________________
7
An Introduction to Semiconductor Devices Chapter 2 Solutions Manual Problem Solutions ______________________________________________________________________________________
Chapter 2 Problem Solutions
λ=
h
− 34
=
p
2.1 E = hν =
hc
λ
2.31x10
⇒