Semiconductor Physics and Devices Solution...
Semiconductor Physics and Devices: Basic Principles, 4th edition Chapter 1 By D. A. Neamen Problem Solutions ______________________________________________________________________________________
Chapter 1 Problem Solutions Then
1.1 (a) fcc: 8 corner atoms 1 / 8 1 atom 6 face atoms 1 / 2 3 atoms Total of 4 atoms per unit cell (b) bcc: 8 corner atoms 1 / 8 1 atom 1 enclosed atom =1 atom Total of 2 atoms per unit cell (c) Diamond: 8 corner atoms 1 / 8 1 atom 6 face atoms 1 / 2 3 atoms 4 enclosed atoms = 4 atoms Total of 8 atoms per unit cell _______________________________________
1.2 (a) Simple cubic lattice: a 2r 3 3 Unit cell vol a 3 2 r 8 r
4 r 3 1 atom per cell, so atom vol 1 3 Then 4 r 3 3 100% 52.4% Ratio 8r 3 (b) Face-centered cubic lattice d d 4r a 2 a 2 2r 2
Unit cell vol a3 2 2 r
3
3
100% 68%
8
Body diagonal d 8 r a 3 a
r
3 8r Unit cell vol a 3
3
3
4 r3 8 atoms per cell, so atom vol 8 3 Then 3 8 4 r 3 Ratio 100% 34% 3 8r 3 _______________________________________
o
(a) a 5.43 A ; From Problem 1.2d,
a
8
r
3
16 2 r 3
o a 3 5.43 3 1.176 A 8 8 Center of one silicon atom to center of
Then r
o
nearest neighbor 2r 2.35 A (b) Number density 8 5 1022 cm 3 3 5.43 10 8 (c) Mass density 22 N At Wt . . 5 10 28.09 NA 6.02 10 23
2.33 grams/cm 3 _______________________________________
3
3
4 r 3 2 atoms per cell, so atom vol 2 3
4r 3 (d) Diamond lattice
1.3
4 r 3 4 atoms per cell, so atom vol 4 3 Then 4 r 3 4 3 Ratio 100% 74% 16 2 r 3 (c) Body-centered cubic lattice 4 d 4r a 3 a r 3 4 Unit cell vol a r 3
Ratio
4 r 3 3
2
Semiconductor Physics and Devices: Basic Principles, 4th edition Chapter 1 By D. A. Neamen Problem Solutions ______________________________________________________________________________________ o
1.4 (a) 4 Ga atoms per unit cell 4 Number density 5.65 10 8
(b) a 21.035 2.07 A
(c) A-atoms: # of atoms 8
3
Density
Density of Ga atoms 2.22 10 22 cm 3 4 As atoms per unit cell Density of As atoms 2.22 10 22 cm 3 (b) 8 Ge atoms per unit cell 8 Number density 8 3 5.65 10
1.5 From Figure 1.15 a 3 (a) d 0.4330a 2 2
1
2.07 10 8
3
1.13 10 23 cm 3 1 B-atoms: # of atoms 6 3 2 3 Density 3 2.07 10 8
Density of Ge atoms 4.44 10 22 cm 3 _______________________________________
1 1 8
3.38 10 cm 3 _______________________________________ 23
1.9 o
(a) a 2r 4.5 A o
0.4330 5.65 d 2.447 A
a (b) d 2 0.7071a 2
# of atoms 8
1 1 8
Number density o
0.70715.65 d 3.995 A _______________________________________
1
4.5 10
8 3
1.097 10 22 cm 3 N At.Wt. Mass density NA
1.0974 10 12.5 22
1.6 a 2 2 2 54.74 sin 3 2 2 a 3 2 109.5 _______________________________________
1.7 o
(a) Simple cubic: a 2r 3.9 A (b) fcc: a (c) bcc: a
o
4r 2 4r
5.515 A
(d) diamond: a
2 4 r
o
9.007 A
3 _______________________________________
1.8 (a) 21.035 2 2 1.035 2rB o
rB 0.4287 A
6.02 1023 0.228 gm/cm3
(b) a
4r
o
5.196 A
3
1 # of atoms 8 1 2 8 Number density
2
5.196 10
8 3
1.4257 10 22cm 3 1.4257 10 22 12.5 Mass density 6.02 10 23 3 0.296gm/cm _______________________________________
o
4.503 A
3
1.10 From Problem 1.2, percent volume of fcc atoms is 74%; Therefore after coffee is ground, Volume = 0.74 cm 3 _______________________________________
Semiconductor Physics and Devices: Basic Principles, 4th edition Chapter 1 By D. A. Neamen Problem Solutions ______________________________________________________________________________________ o
1.11 o
(b) a 1.8 1.0 2.8 A (c) Na: Density
1 / 2
2.8 10
8 3
2.28 10 22cm 3 Cl: Density 2.28 10 22 cm 3 (d) Na: At. Wt. = 22.99 Cl: At. Wt. = 35.45 So, mass per unit cell 1 1 22.99 35.45 2 2 4.85 10 23 6.02 10 23 Then mass density 4.85 10 23 2.21 grams/cm 3 8 3 2.8 10 _______________________________________
1.12 o
(a) a 3 2 2.2 2 1.8 8 A o
Then a 4.62 A Density of A: 1 1.01 10 22 cm 3 8 3 4.62 10 Density of B: 1 1.01 10 22 cm 3 8 3 4.62 10 (b) Same as (a) (c) Same material _______________________________________
1.13
22.2 21.8
2
4.687 10 14 cm 2 o
For 1.12(b), B-atoms: a 4.619 A 1
4.687 10 14cm 2 a2 For 1.12(a) and (b), Same material
Surface density
o
For 1.12(b), A-atoms; a 4.619 A Surface density 1 3.315 10 14 cm 2 2 a 2 B-atoms; Surface density 1 14 2 2 3.315 10 cm a 2 For 1.12(a) and (b), Same material _______________________________________
1.14 (a) Vol. Density
1 a 3o
Surface Density
1
ao2 2
(b) Same as (a) _______________________________________
1.15 (i) (110) plane (see Figure 1.10(b)) (ii) (111) plane (see Figure 1.10(c))
o
4.619 A 3 (a) For 1.12(a), A-atoms 1 1 Surface density 2 a 4.619 10 8
a
(b) For 1.12(a), A-atoms; a 4.619 A Surface density 1 3.315 10 14 cm 2 a2 2 B-atoms; Surface density 1 3.315 10 14cm 2 2 a 2
1 1 (iii) (220) plane , , 1, 1, 0 2 2 Same as (110) plane and [110] direction 1 1 1 (iv) (321) plane , , 2, 3, 6 3 2 1 Intercepts of plane at p 2,q 3,s 6 [321] direction is perpendicular to (321) plane _______________________________________
Semiconductor Physics and Devices: Basic Principles, 4th edition Chapter 1 By D. A. Neamen Problem Solutions ______________________________________________________________________________________
1.16 (a)
1 1 1 , , 313 1 3 1 (b)
1 1 1 , , 121 4 2 4 _______________________________________ 1.17
1 1 1 Intercepts: 2, 4, 3 , , 2 4 3 (634) plane _______________________________________ 1.18 o
(a) d a 5.28 A o a 2 3.734 A 2 o a 3 (c) d 3.048 A 3 _______________________________________
(b) d
1.19
(a) Simple cubic (i) (100) plane: Surface density
1 1 a2 4.73 108
2
(ii) (110) plane: 1
Surface density a
2
2
3.16 10 14cm 2 (iii) (111) plane: 1 Area of plane bh 2 o
where b a 2 6.689 A Now a 2 2 2 h a 2 2
2
3 a 2 4
o 6 4.73 5.793 A So h 2
6.32 10 14 cm 2 (iii) (111) plane: 1 3 6 Surface density 16 19.3755 10 14 2.58 10 cm 2 (c) fcc (i) (100) plane: 2 Surface density 2 8.94 1014 cm 2 a (ii) (110) plane: 2 Surface density 2 a 2
6.32 10 14 cm 2 (iii) (111) plane: 1 1 3 3 6 2 Surface density 16 19.3755 10 15 1.03 10 cm 2 _______________________________________
4.47 10 14 cm 2
Area of plane 1 6.68923 108 5.7930410 8 2 19.3755 10 16 cm 2 1 3 6 Surface density 19.3755 10 16 2.58 10 14 cm 2 (b) bcc (i) (100) plane: 1 Surface density 2 4.47 1014 cm 2 a (ii) (110) plane: 2 Surface density 2 a 2
2
1.20 (a) (100) plane: - similar to a fcc: 2 Surface density 2 5.43 10 8
6.78 10 cm 2 14
(b) (110) plane: Surface density
4
2 5.43 10 8
2
9.59 10 14 cm 2
Semiconductor Physics and Devices: Basic Principles, 4th edition Chapter 1 By D. A. Neamen Problem Solutions ______________________________________________________________________________________ (c) (111) plane: Surface density
2
3 2 5.43 10 8
2
7.83 10 cm 2 _______________________________________ 14
1.21
a
4r 2
4 2.37
o
6.703 A
2 1 1 8 6 4 8 2 (a) #/cm 3 3 a 6.703 10 8
(a)
3
o a 2 6.703 2 4.74 A 2 2 1 1 (d) # of atoms 3 3 2 6 2 Area of plane: (see Problem 1.19)
(c) d
3 100% 10 %
Volume density
o 6a 8.2099 A 2
Area 1 1 bh 9.4786 10 8 8.2099 10 8 2 2 15 3.8909 10 cm 2
1.26
o
b a 2 9.4786 A
#/cm 2
5 1022 2 1015
3.148 10 cm 2
5 1017
1.25 (a) Fraction by weight 2 1016 10.82 7 1.542 10 22 5 10 28.06 (b) Fraction by weight 18 10 30.98 5 2.208 10 5 1022 28.06 _______________________________________
6 100% 4 10 % 5 1022 _______________________________________
(b)
14
h
1.24
1.328 10 22 cm 3 1 1 4 2 2 4 2 (b) #/cm a2 2 2 2 6.703 10 8 2
1.23 Density of GaAs atoms 8 4.44 1022 cm 3 3 5.65 10 8 An average of 4 valence electrons per atom, So Density of valence electrons 23 1.77 10 cm 3 _______________________________________
1 d3
2 10 16cm 3 o
So d 3.684 10 6 cm d 368.4 A
2
3.8909 10 = 5.14 10 14 cm 2 15
o a 3 6.703 3 3.87 A 3 3 _______________________________________
d
1.22 3 Density of silicon atoms 510 22cm and 4 valence electrons per atom, so 3 Density of valence electrons 210 23 cm _______________________________________
o
We have a o 5.43 A d 368.4 67.85 ao 5.43 _______________________________________ Then
1.27 Volume density
1 d3
4 10 15cm 3 o
So d 6.30 10 6 cm d 630 A o
We have a o 5.43 A 630 d 116 a o 5.43 _______________________________________ Then
Semiconductor Physics and Devices: Basic Principles, 4th edition Chapter 2 By D. A. Neamen Problem Solutions ______________________________________________________________________________________
Chapter 2 2.6
2.1 Sketch _______________________________________ 2.2 Sketch _______________________________________ 2.3 Sketch _______________________________________
(a) p
h
6.625 10 34
550 10 27 1.205 10 kg-m/s p 1.2045 10 27 1.32 10 3m/s m 9.11 10 31 9
or 1.32 10 5 cm/s h 6.625 1034 (b) p 440 10 9 1.506 10 kg-m/s p 1.5057 10 27 3 1.65 10 m/s m 9.11 10 31 or 1.65 10 5 cm/s (c) Yes _______________________________________ 27
2.4 From Problem 2.2, phase
2 x
t
= constant Then dx 2 dx 0, p dt dt 2 2 x From Problem 2.3, phase t
= constant Then dx 2 dx 0, p dt dt 2 _______________________________________
2.7 (a) (i)
p 2mE 2 9.11 10 31 1.2 1.6 10 19 25
5.915 10 kg-m/s h 6.625 1034 9 1.12 10 m p 5.915 1025 o
or 11.2 A
(ii) p 2 9.11 10 31 12 1.6 10 19
2.5 E h
hc
hc
E Gold: E 4.90 eV 4.90 1.6 10 19 J So, 6.625 10 34 3 10 10 2.54 10 5 cm 4.90 1.6 10 19 or 0.254 m
Cesium: E 1.90 eV 1.90 1.6 10 19 J So, 6.625 10 34 3 10 10 6.54 10 5 cm 1.90 1.6 10 19 or 0.654 m _______________________________________
1.87 10 6.625 10 34
24
1.8704 10 24
kg-m/s
3.54 10 10 m
o
or 3.54 A
5.915 10
24
(iii) p 2 9.11 10 31 120 1.6 10 19
34
kg-m/s
6.625 10 10 1.12 10 m 5.915 10 24 o
or 1.12 A
Semiconductor Physics and Devices: Basic Principles, 4th edition Chapter 2 By D. A. Neamen Problem Solutions ______________________________________________________________________________________ (b)
p 2 1.67 10
27
2.10
1.21.6 10 19
E avg
3 3 kT 0.0259 0.03885 eV 2 2
Now
6.625 10 34
or
8.56 10 6 cm/s
o
2.8
h
85 10 10 26 7.794 10 kg-m/s p 7.794 10 26 8.56 10 4 m/s 31 m 9.11 10
2.532 10 23kg-m/s 6.625 10 34 11 2.62 10 m 2.532 10 23 or 0.262 A _______________________________________
p
(a)
p avg 2mE avg
2 9.11 10
0.038851.6 10
31
19
or p avg 1.064 10 25 kg-m/s
Now
1 1 m 2 9.11 10 31 8.56 10 4 2 2 21 3.33 10 J 21 3.334 10 or E 2.08 10 2 eV 19 1.6 10 1 2 (b) E 9.11 10 31 8 103 2 23 2.915 10 J 23 2.915 10 1.82 10 4 eV or E 1.6 10 19 p m 9.11 10 31 8 103
E
34 h 6.625 10 9 6.225 10 m 25 p 1.064 10
2
27
7.288 10 kg-m/s h 6.625 10 35 9.09 10 8 m p 7.288 10 27
or o
62.25 A
o
_______________________________________
or 909 A _______________________________________
2.9
E p h p
2.11
hc
p
Now 2 h 1 h pe Ee and pe e 2m e 2m Set E p E e and p 10 e
Then 2
2
1 h 1 10h p 2 m e 2m p which yields 100h p 2 mc hc hc 2mc2 2mc Ep E p 100h 100
31
2 9.11 10 3 10 100
8
2
1.64 10 15J 10.25 keV _______________________________________
6.625 10 3 10 34
1 10
8
10
1.99 10 J 15
2
Ee
hc
hc
(a) E h
Now
E 1.99 10 15 19 e 1.6 10 4 V 1.24 10 V 12.4 kV E e V V
(b) p 2 mE 2 9.11 10 31 1.99 10 15
23
6.02 10 kg-m/s Then h 6.625 10 34 1.10 10 11 m 23 p 6.02 10 or o
0.11 A _______________________________________
Semiconductor Physics and Devices: Basic Principles, 4th edition Chapter 2 By D. A. Neamen Problem Solutions ______________________________________________________________________________________
2.12 1.054 10 34 p x 10 6
1.054 10 kg-m/s _______________________________________ 28
2.13 (a) (i) p x p
1.054 10 12 1010
34
8.783 10 26 kg-m/s
p2 2 m p p p 2p p m 2m
dE d p (ii) E dp dp
Now p 2mE
2 9 10 31 16 1.6 10 19
24
2.147 10 kg-m/s 2.1466 1024 8.783 1026 so E 9 10 31 2.095 10 19 J 2.095 1019 or E 1.31 eV 1.6 10 19 (b) (i) p 8.783 10 26 kg-m/s
(ii) p 2 5 10 28 16 1.6 10 19
23
5.06 10 kg-m/s 5.06 10 23 8.783 10 26 E 5 10 28 8.888 10 21 J 8.888 10 21 5.55 10 2 eV or E 1.6 10 19 _______________________________________
2.14 34 1.054 10 1.054 10 32 kg-m/s 2 x 10 p 1.054 10 32 p m m 1500
p
7 10 m/s _______________________________________ 36
2.15 (a) E t 1.054 10 34 8.23 10 16 s t 0.8 1.6 10 19
1.054 10 34 x 1.5 10 10 7.03 10 25 kg-m/s _______________________________________
(b) p
2.16 (a) If 1 x, t and 2 x, t are solutions to Schrodinger's wave equation, then x , t 2 2 1 x, t V x 1 x , t j 1 2 t 2m x and 2 x , t 2 2 2 x, t V x 2 x , t j t 2m x 2 Adding the two equations, we obtain 2 2 1 x , t 2 x , t 2m x 2 V x 1 x, t 2 x, t x, t 2 x, t t 1 which is Schrodinger's wave equation. ...