Fundamental of Semiconductor

Fundamental of
Semiconductor
Chapter 1
Learning outcome
• Explain the basic concept of doping and carrier transport in
semiconductor. (Cognitive, Understanding – Level 2)
Objectives
To understand
the charge
transport in
To understand semiconductor
the electronic
structures and
basic properties
of
semiconductors
To introduce
atomic
structure and
energy band in
solids
Outline
Energy bands in Semiconductor

semiconductors • Intrinsic
History of • Energy band in solid • Extrinsic
Semiconductors • Formation of band • Doping with
• Metal, semiconductor, donor/acceptor
insulator • Electrical conductivity
Topic 1
History of Semiconductors
Q. What is the noteworthy
things about this field?
Remarkable Point
• One of the noteworthy things about this field, as in many
other areas of technology, is how little the fundamental
principles change over time. Leaving us to wonder where
technology is taking us
• However, if we take a moment to consider that the majority of
all the devices in use were invented decades ago and that
design techniques appearing in texts as far back as the 1930s
are still in use, we realize that most of what we see is
primarily a steady improvement in construction techniques,
general characteristics, and application techniques rather
than the development of new elements and fundamentally
new designs.
……60 years ago
• The first integrated circuit (IC) was developed by Jack Kilby
while working at Texas Instruments in 1958. However, the
Intel Core i7 Extreme Edition Processor has 731 million
transistors in a package.
• In 1965, Dr. Gordon E. Moore presented a paper predicting
that the transistor count in a single IC chip would double
every two years.
• Now, almost 55 years, later we find that his prediction is
amazingly accurate and expected to continue for the next few
decades.
Electronic technology grows rapidly … (doubles every year)
What is electronics?
• Science of study of flow and control of electrons (electricity).

• An electronic component is any physical entity in an
electronic system used to affect the electrons or their
associated fields in a manner consistent with the intended
function of the electronic system
• Most electronic devices use semiconductor components to
perform electron control.
• The first device to be introduced here is the simplest of all
electronic devices, yet has a range of applications that seems
endless.
What is semiconductors?
Conductors
Insulators
Semiconductor
s
What is semiconductors?
Conductor is applied to
any material that will
support a generous flow
of charge when a
A semiconductor, voltage source is
therefore, is a material applied across its Insulator is a material
that has a conductivity terminals. that offers a very low
level somewhere level of conductivity
between the extremes under pressure from an
of an insulator and a The prefix semi is applied voltage source.
conductor. normally applied to a
range of levels midway
between two limits.
Semiconductor Materials
Semiconductors are a special class of elements having a

conductivity between that of a good conductor and that of an
insulator.
• They fall into two classes: single crystal and compound
• Single crystal: Germanium (Ge) and silicon (Si).
• Compound: gallium arsenide (GaAs), cadmium sulfide (CdS),
gallium nitride (GaN), gallium arsenide phosphide (GaAsP)
• The three semiconductors used most frequently in the
construction of electronic devices are Ge, Si, and GaAs
History
• Diode , in 1939 was using Ge
• Transistor, in 1947 was using Ge
• In1954 Si was used in Transistor because Si is less
temperature sensitive and abundantly available.
• High speed transistor was using GaAs in 1970 (which is 5
times faster compared to Si).
• Si, Ge and GaAs are the semiconductor of choice
COVALENT BONDING AND INTRINSIC MATERIALS
• To fully appreciate why Si, Ge, and GaAs are the

semiconductors of choice for the electronics industry requires
some understanding of the atomic structure of each and how
the atoms are bound together to form a crystalline structure
• The fundamental components of an atom are the electron,
proton, and neutron. In the lattice structure, neutrons and
protons form the nucleus and electrons appear in fixed orbits
around the nucleus
Atomic Structure
Atomic Structure
Covalent Bonding
Covalent Bonding
Covalent Bonding
Intrinsic Semiconductor
• The term intrinsic is applied to any semiconductor material

that has been carefully refined to reduce the number of
impurities to a very low level—essentially as pure as can be
made available through modern technology.
Energy Levels
Energy Levels
N-Type and P-Type Materials

Fundamental of Semiconductor

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Fundamental of Semiconductor

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Fundamental of

Energy bands in Semiconductor

• Science of study of flow and control of electrons (electricity).

Semiconductors are a special class of elements having a

• To fully appreciate why Si, Ge, and GaAs are the

• The term intrinsic is applied to any semiconductor material

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