Semiconductor Device Physics

woundcallousSemiconductor

Nov 1, 2013 (3 years and 10 months ago)

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President University

Erwin Sitompul

SDP

1
/
1

Dr.
-
Ing. Erwin Sitompul

President University

Lecture
1

Semiconductor Device Physics

http://zitompul.wordpress.com

President University

Erwin Sitompul

SDP

1
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Textbook:

“Semiconductor Device Fundamentals”,

Robert F. Pierret, International Edition,
Addison Wesley, 1996.

Textbook and Syllabus

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

Semiconductor Device Physics

President University

Erwin Sitompul

SDP

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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.


Semiconductor Device Physics

President University

Erwin Sitompul

SDP

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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).


Semiconductor Device Physics

Grade Policy


Heading of Homework Papers (Required)

President University

Erwin Sitompul

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Grade Policy

Grade Policy:


Ex
tra 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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Semiconductor Device Physics

President University

Erwin Sitompul

SDP

1
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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.

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Erwin Sitompul

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No recognizable

long
-
range order

Completely ordered

in segments

Entire solid is made up of

atoms in an orderly

three
-

dimensional array

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 10
9

semiconductor atom.


Intentional impurity ranging from 1 per 10
8

to 1 per 10
3
.


Most devices fabricated today employ crystalline
semiconductors.

polycrystalline

amorphous crystalline

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Erwin Sitompul

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Semiconductor Materials

Elemental
:



Si, Ge, C


Compound
:

IV
-
IV

SiC



III
-
V

GaAs, GaN



II
-
VI

CdSe


Alloy
:


Si
1
-
x
Ge
x



Al
x
Ga
1
-
x
As


Chapter 1

Semiconductors: A General Introduction

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Erwin Sitompul

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From Hydrogen to Silicon

Chapter 1

Semiconductors: A General Introduction

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Erwin Sitompul

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The Silicon Atom

Chapter 1

Semiconductors: A General Introduction


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

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The Si Crystal

“Diamond Lattice”

a

Chapter 1

Semiconductors: A General Introduction


Each Si atom has 4 nearest
neighbors.


Atom
lattice constant

(length of the unit cell side)


a
=

5.431
A, 1A
=
10

10
m

°

°


Each cell contains:


8 corner atoms


6 face atoms


4 interior atoms

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Erwin Sitompul

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How Many Silicon Atoms per cm

3
?

Chapter 1

Semiconductors: A General Introduction


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

cm
3


Density of silicon atom



= (8 atoms) / (cell volume)



=
5 x 10
22

atoms/cm
3

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Erwin Sitompul

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Compound Semiconductors

Chapter 1

Semiconductors: A General Introduction


“Zincblende” structure


III
-
V compound semiconductors: GaAs, GaP, GaN,
etc.

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Crystallographic Notation

Notation

Interpretation

(

h k l
)

crystal plane

{

h k l
}

equivalent planes

[

h k l
]

crystal direction

<

h k l
>

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.)

Miller Indices

Chapter 1

Semiconductors: A General Introduction

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Crystallographic Planes

(632) plane

(001) plane

(221) plane

Chapter 1

Semiconductors: A General Introduction

_

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Crystallographic Planes

Chapter 1

Semiconductors: A General Introduction

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Crystallographic Planes of Si Wafers

Chapter 1

Semiconductors: A General Introduction


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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Crystal Growth Until Device Fabrication

Chapter 1

Semiconductors: A General Introduction

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Unit cell:

View in <100> direction

Crystallographic Planes of Si

View in <110> direction

Chapter 1

Semiconductors: A General Introduction

View in <111> direction

President University

Erwin Sitompul

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Greek Alphabet

Chapter 1

Semiconductors: A General Introduction


pie


fie


k
-
eye


sigh


zz
-
eye


taw


new


mew