Semiconductor Device Physics
Lecture 1
Dr.-Ing. Erwin Sitompul
President University
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President University
Erwin Sitompul
SDP 1/1
Semiconductor Device Physics
Textbook and Syllabus
Textbook:
“Semiconductor Device Fundamentals”,
Robert F. Pierret, International Edition,
Addison Wesley, 1996.
Syllabus:
Chapter 1: Semiconductors: A General Introduction
Chapter 2: Carrier Modeling
Chapter 3: Carrier Action
Chapter 5: pn Junction Electrostatics
Chapter 6: pn Junction Diode: I–V Characteristics
Chapter 7: pn Junction Diode: Small-Signal Admittance
Chapter 8: pn Junction Diode: Transient Response
Chapter 14: MS Contacts and Schottky Diodes
Chapter 9: Optoelectronic Diodes
Chapter 10: BJT Fundamentals
Chapter 11: BJT Static Characteristics
Chapter 12: BJT Dynamic Response Modeling
President University
Erwin Sitompul
SDP 1/2
Semiconductor Device Physics
Grade Policy
Grade Policy:
Final Grade = 10% Homework + 20% Quizzes +
30% Midterm Exam + 40% Final Exam +
Extra Points
 Homeworks will be given in fairly regular basis. The average
of homework grades contributes 10% of final grade.
 Homeworks are to be written on A4 papers, otherwise they
will not be graded.
 Homeworks must be submitted on time. If you submit late,
< 10 min.
 No penalty
10 – 60 min.  –20 points
> 60 min.
 –40 points
 There will be 3 quizzes. Only the best 2 will be counted.
The average of quiz grades contributes 20% of final grade.
President University
Erwin Sitompul
SDP 1/3
Semiconductor Device Physics
Grade Policy
• Heading of Homework Papers (Required)
Grade Policy:
 Midterm and final exam schedule will be announced in time.
 Make up of quizzes and exams will be held one week after
the schedule of the respective quizzes and exams.
 The score of a make up quiz or exam can be multiplied by 0.9
(the maximum score for a make up is 90).
President University
Erwin Sitompul
SDP 1/4
Semiconductor Device Physics
Grade Policy
Grade Policy:
 Extra points will be given every time you solve a problem in
front of the class. You will earn 1 or 2 points.
 Lecture slides can be copied during class session. It also will
be available on internet around 3 days after class. Please
check the course homepage regularly.
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President University
Erwin Sitompul
SDP 1/5
Chapter 1
Semiconductors: A General Introduction
What is a Semiconductor?
 Low resistivity
 “conductor”
 High resistivity
 “insulator”
 Intermediate resistivity  “semiconductor”
 The conductivity (and at the same time the resistivity) of
semiconductors lie between that of conductors and insulators.
President University
Erwin Sitompul
SDP 1/6
Chapter 1
Semiconductors: A General Introduction
What is a Semiconductor?
 Semiconductors are some of the purest solid materials in
existence, because any trace of impurity atoms called “dopants”
can change the electrical properties of semiconductors
drastically.
 Unintentional impurity level:
1 impurity atom per 109 semiconductor atom.
 Intentional impurity ranging from 1 per 108 to 1 per 103.
No recognizable
long-range order
Entire solid is made up of
atoms in an orderly
three- dimensional array
Completely ordered
in segments
polycrystalline amorphous crystalline
 Most devices fabricated today employ crystalline
semiconductors.
President University
Erwin Sitompul
SDP 1/7
Chapter 1
Semiconductors: A General Introduction
Semiconductor Materials
Elemental:
Si, Ge, C
Compound:
IV-IV
III-V
II-VI
Alloy:
Si1-xGex
AlxGa1-xAs
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SiC
GaAs, GaN
CdSe
Erwin Sitompul
SDP 1/8
Chapter 1
Semiconductors: A General Introduction
From Hydrogen to Silicon
# of Electrons
1
2
3
Z Name 1s 2s 2p 3s 3p 3d
President University
Notation
1
1H
1
1s
2 He
2
1s 2
3 Li
2
1
1s 2 2s 1
4 Be
2
2
1s 2 2s 2
5B
2
2
1
1s 2 2s 2 2p1
6C
2
2
2
1s 2 2s 2 2p2
7N
2
2
3
1s 2 2s 2 2p3
8O
2
2
4
1s 2 2s 2 2p4
9F
2
2
5
1s 2 2s 2 2p5
10 Ne
2
2
6
1s 2 2s 2 2p6
11 Na
2
2
6
1
1s 2 2s 2 2p6 3s 1
12 Mg
2
2
6
2
1s 2 2s 2 2p6 3s 2
13 Al
2
2
6
2
1
1s 2 2s 2 2p6 3s 2 3p1
14 Si
2
2
6
2
2
1s 2 2s 2 2p6 3s 2 3p2
15 P
2
2
6
2
3
1s 2 2s 2 2p6 3s 2 3p3
16 S
2
2
6
2
4
1s 2 2s 2 2p6 3s 2 3p4
17 Cl
2
2
6
2
5
1s 2 2s 2 2p6 3s 2 3p5
18 Ar
2
2
6
2
6
1s 2 2s 2 2p6 3s 2 3p6
Erwin Sitompul
SDP 1/9
Chapter 1
Semiconductors: A General Introduction
The Silicon Atom
 14 electrons occupying the first 3 energy levels:
 1s, 2s, 2p orbitals are filled by 10 electrons.
 3s, 3p orbitals filled by 4 electrons.
 To minimize the overall energy, the 3s and
3p orbitals hybridize to form four
tetrahedral 3sp orbital.
 Each has one electron and is capable of
forming a bond with a neighboring atom.
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Erwin Sitompul
SDP 1/10
Chapter 1
Semiconductors: A General Introduction
The Si Crystal
• Each Si atom has 4 nearest
neighbors.
• Atom lattice constant
(length of the unit cell side)
° 1A=10
°
–10m
a = 5.431A,
• Each cell contains:
8 corner atoms
6 face atoms
4 interior atoms
a
“Diamond Lattice”
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Erwin Sitompul
SDP 1/11
Chapter 1
Semiconductors: A General Introduction
How Many Silicon Atoms per cm–3?
 Number of atoms in a unit cell:
 4 atoms completely inside cell
 Each of the 8 atoms on corners are shared among 8 cells
 count as 1 atom inside cell
 Each of the 6 atoms on the faces are shared among 2 cells
 count as 3 atoms inside cell
Total number inside the cell = 4 + 1 + 3 = 8
 Cell volume = (.543 nm)3 = 1.6 x 10–22 cm3
 Density of silicon atom
= (8 atoms) / (cell volume)
= 5 x 1022 atoms/cm3
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Erwin Sitompul
SDP 1/12
Chapter 1
Semiconductors: A General Introduction
Compound Semiconductors
 “Zincblende” structure
 III-V compound semiconductors: GaAs, GaP, GaN, etc.
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Erwin Sitompul
SDP 1/13
Chapter 1
Semiconductors: A General Introduction
Crystallographic Notation
Miller Indices
Notation
Interpretation
(hkl)
crystal plane
{hkl}
equivalent planes
[hkl]
crystal direction
<hkl>
equivalent directions
h: inverse x-intercept of plane
k: inverse y-intercept of plane
l: inverse z-intercept of plane
(h, k and l are reduced to 3
integers having the same ratio.)
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Erwin Sitompul
SDP 1/14
Chapter 1
Semiconductors: A General Introduction
Crystallographic Planes
(632) plane
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(001) plane
Erwin Sitompul
_
(221) plane
SDP 1/15
Chapter 1
Semiconductors: A General Introduction
Crystallographic Planes
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Erwin Sitompul
SDP 1/16
Chapter 1
Semiconductors: A General Introduction
Crystallographic Planes of Si Wafers
 Silicon wafers are usually cut along a {100} plane with a flat or
notch to orient the wafer during integrated-circuit fabrication.
 The facing surface is polished and etched yielding mirror-like
finish.
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Erwin Sitompul
SDP 1/17
Chapter 1
Semiconductors: A General Introduction
Crystal Growth Until Device Fabrication
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Erwin Sitompul
SDP 1/18
Chapter 1
Semiconductors: A General Introduction
Crystallographic Planes of Si
Unit cell:
View in <111> direction
View in <100> direction
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View in <110> direction
Erwin Sitompul
SDP 1/19
Chapter 1
Semiconductors: A General Introduction
Greek Alphabet
—new
—zz-eye
—pie
—taw
—fie
—k-eye
—sigh
—mew
President University
Erwin Sitompul
SDP 1/20