Semiconductor

1. What is Semiconductor?
 A semiconductor is a material that has electrical conductivity between
that of a conductor and an insulator. It is typically made of a crystalline
solid, such as silicon or germanium.
What is semiconductor doping?
Semiconductor doping is a process of adding impurities into a
semiconductor material to modify its electrical properties. This is also
known as extrinsic semiconductor.
Adding impurities to semiconductors is a process that allows engineers
to control the electrical, optical, and structural properties of the material.
This customization is essential for designing and manufacturing
semiconductor devices in various applications.
Two common types of dopants used in semiconductors are:
1. p-type. 2 . n-type.

2. What is p type semiconductor?
 An n-type semiconductor is a type of semiconductor material that
has been doped with trivalent impurities of the periodic table.
How to create p type semiconductor?
 Start with an intrinsic semiconductor: Begin with a high-purity
semiconductor material, such as silicon (Si) or germanium (Ge).
Intrinsic semiconductors have an equal number of electrons and
holes.
 Select a group III impurity: Choose an element from group III of the
periodic table, such as boron (B), aluminum (Al), or gallium (Ga).
These elements have one less valence electron than the
semiconductor material, creating a "hole" in the lattice structure.
 Doping process: Introduce the group III impurity atoms into the
semiconductor crystal lattice through a process called doping. This
is typically achieved by mixing the impurity element with the
semiconductor material.

3.  In a p-type semiconductor, current flow occurs primarily due to
the movement of positive charge carriers, known as "holes."
 Holes are created in the valence band of the semiconductor
material due to the presence of group III impurity atoms.
 When a voltage is applied across the p-type semiconductor, the
electric field causes the holes to move towards the negatively
charged terminal.
 As the holes move, they leave behind positively charged ionized
impurity atoms, creating fixed positive charges in the crystal
lattice.
 Electrons from the surrounding material can fill these holes,
creating new holes elsewhere in the lattice. The majority carriers
are the holes.
 The movement of holes and electrons contributes to the flow of
How current passes through p-type semiconductor?

4. What is n type semiconductor?
 An n-type semiconductor is a type of semiconductor material that
has been doped with pentavalent impurities of the periodic table.
How to create n-type semiconductor?
 Start with an intrinsic semiconductor: Begin with a high-purity
semiconductor material, such as silicon (Si) or germanium (Ge).
Intrinsic semiconductors have an equal number of electrons and
holes.
 Select a group V impurity: Choose an element from group V of the
periodic table, such as phosphorus (P), arsenic (As), or antimony
(Sb). These elements have one more valence electron than the
semiconductor material, creating an extra electron available for
conduction.
 Doping process: Introduce the group V impurity atoms into the
semiconductor crystal lattice through a process called doping. This
can be achieved by mixing the impurity element with the
semiconductor material.

5.  In an n-type semiconductor, current flow occurs primarily due to the
movement of negative charge carriers, known as electrons.
 N-type semiconductors are created by introducing impurity atoms
from group V of the periodic table, such as phosphorus (P) or
arsenic (As), which have an extra valence electron compared to the
semiconductor material.
 The additional valence electron of the impurity atom becomes a free
electron available for conduction.
 When a voltage is applied across the n-type semiconductor, the
electric field causes the free electrons to move towards the positively
charged terminal.
 The movement of electrons contributes to the flow of current in the
n-type semiconductor.
How current passes through n-type semiconductor?

6. Usage of extrinsic semiconductors:
 Electronic Devices: Extrinsic semiconductors are fundamental to
the operation of a wide range of electronic devices.
 Transistors: Extrinsic semiconductors are employed to create the
necessary p-n junctions and control the flow of current in
transistors.
 Diodes: Extrinsic semiconductors are utilized to fabricate diodes,
which allow the flow of current in only one direction.
 Integrated Circuits: Extrinsic semiconductors are utilized to
fabricate diodes, which allow the flow of current in only one
direction.
 Solar Cells: Extrinsic semiconductors play a crucial role in
photovoltaic devices, commonly known as solar cells.
 Sensors: Extrinsic semiconductors are utilized in various sensor
technologies, including temperature sensors, pressure sensors,
light sensors, and gas sensors.

7. Negative aspects of Extrinsic semiconductors:
 Introduction of Impurities.
 Carrier Recombination.
 Increased Leakage Current.
 Manufacturing Complexity and Cost.
 Dopant Diffusion and Activation.
 Impact on Thermal Properties.
It's important to note that while these negative aspects exist, they
can be mitigated through careful design, optimization, and control
during the doping process. Semiconductor manufacturers
continuously strive to overcome these challenges to improve
device performance, reliability, and efficiency.