The document discusses P-N junctions, which are formed at the interface between P-type and N-type semiconductors. When these materials come into contact, majority charge carriers diffuse across the junction, leaving behind charged dopant ions. This creates an electric field and depletion region across the junction. At equilibrium with no applied voltage, a built-in potential barrier forms that prevents further carrier recombination. P-N junctions can be forward or reverse biased by an external voltage, affecting the electric field and current flow. They are the basic components of many semiconductor devices such as diodes, transistors, and solar cells.
This ppt is about semiconductor diodes.You can get every basic information about PN junction diode and its working and some more information about the semiconductors.
The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET). It has an insulated gate, whose voltage determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. Although FET is sometimes used when referring to MOSFET devices, other types of field-effect transistors also exist.
The attached narrated power point presentation explains the construction, working and applications of PN Junction Diodes. The material will be useful for KTU first year students who prepare for the subject EST 130, Part B, Basic Electronics Engineering.
This ppt is about semiconductor diodes.You can get every basic information about PN junction diode and its working and some more information about the semiconductors.
The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET). It has an insulated gate, whose voltage determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. Although FET is sometimes used when referring to MOSFET devices, other types of field-effect transistors also exist.
The attached narrated power point presentation explains the construction, working and applications of PN Junction Diodes. The material will be useful for KTU first year students who prepare for the subject EST 130, Part B, Basic Electronics Engineering.
The Zener diode is a heavily doped diode which, as a result of doping, has a very narrow depletion region. This allows the diode to be operated in the reverse biased region of the characteristic curve without damaging the PN junction.
“Zener Effect”: The area of Zener diode operation (<5V) where the Diode maintains a constant voltage output while operating reverse biased.
“Avalanche Effect”: >5V applied to the diode while reverse biased which tends to cause the diode to eventually breakdown due to heat generation within the lattice structure of the crystal.
Because of its higher temperature and current capability, silicon is usually preferred in manufacture of Zener Diodes
Zener Diodes provide a stable reference voltage for use in power supplies, voltmeter & other instruments, voltage regulators.
The three terminals of the FET are known as Gate, Drain, and Source.
It is a voltage controlled device, where the input voltage controls by the output current.
In FET current used to flow between the drain and the source terminal. And this current can be controlled by applying the voltage between the gate and the source terminal.
So this applied voltage generate the electric field within the device and by controlling these electric field we can control the flow of current through the device.
Pn junction diode by sarmad baloch
I AM SARMAD KHOSA
BSIT (5TH A)
(ISP)
FACEBOOK PAGLE::
https://www.facebook.com/LAUGHINGHLAUGHTER/
YOUTUBE CHANNEL:::
https://www.youtube.com/channel/UCUjaIeS-DHI9xv-ZnBpx2hQ
Field Effect Transistor is a transistor that is voltage controlled devices. It has higher input impedance and less sensitive to temperature variations.
The Zener diode is a heavily doped diode which, as a result of doping, has a very narrow depletion region. This allows the diode to be operated in the reverse biased region of the characteristic curve without damaging the PN junction.
“Zener Effect”: The area of Zener diode operation (<5V) where the Diode maintains a constant voltage output while operating reverse biased.
“Avalanche Effect”: >5V applied to the diode while reverse biased which tends to cause the diode to eventually breakdown due to heat generation within the lattice structure of the crystal.
Because of its higher temperature and current capability, silicon is usually preferred in manufacture of Zener Diodes
Zener Diodes provide a stable reference voltage for use in power supplies, voltmeter & other instruments, voltage regulators.
The three terminals of the FET are known as Gate, Drain, and Source.
It is a voltage controlled device, where the input voltage controls by the output current.
In FET current used to flow between the drain and the source terminal. And this current can be controlled by applying the voltage between the gate and the source terminal.
So this applied voltage generate the electric field within the device and by controlling these electric field we can control the flow of current through the device.
Pn junction diode by sarmad baloch
I AM SARMAD KHOSA
BSIT (5TH A)
(ISP)
FACEBOOK PAGLE::
https://www.facebook.com/LAUGHINGHLAUGHTER/
YOUTUBE CHANNEL:::
https://www.youtube.com/channel/UCUjaIeS-DHI9xv-ZnBpx2hQ
Field Effect Transistor is a transistor that is voltage controlled devices. It has higher input impedance and less sensitive to temperature variations.
This presentation gives a lot of information about
Semiconductor Devices.This is presented by Rajesh Kumar Sangani from Rajiv Gandhi University of Knowledge Technologies,Basar Dist
Adilabad,A.P,India.
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Lecture on Introduction of Semiconductor at North South University as the undergraduate course (ETE411)
=======================
Dr. Mashiur Rahman
Assistant Professor
Dept. of Electrical Engineering and Computer Science
North South University, Dhaka, Bangladesh
http://mashiur.biggani.org
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
2. I
+ V –
Circuit symbol
P-N Junction
Donor ions
N-type
P-type
P-type semiconductor in contact with
N-type semiconductor forms a P-N
junction
To a semiconductor, one side electrons
and other side holes are injected
Or to a P-type semiconductor a layer of
electrons are diffused or vice versa.
P-N junctions are the basic unit of all
semiconductor devices; at least one
junction
Used as rectifiers, switching devices,
solar cells, laser diodes and LEDs
4. n-typep-type
NdNa
pp0= Na
nn0= Nd
a
2
i
0p
N
n
n
d
2
i
0n
N
n
p
Step Junction
P and N sides are UNIFORMLY doped with acceptor impurity Na
and donor impurity Nd the idealised junction is called a step
junction.
6. BASIC STRUCTURE
1.Due to density gradient of the majority carriers across the junction, carrier
diffusion takes place.
2. Recombination of majority carriers across the junction leaves behind positive
dopant ions on the N-side and negative dopant ions on the P-side.
3. Separation of charge creates a POTENTIAL DIFFERENCE at the junction and an
ELECTRIC FIELD is established directed from N to P side of the junction.
4. In a region on both sides of the junction free carriers (electrons and holes) are
absent, this is called DEPLETION LAYER or SPACE CHARGE REGION
5. Outside this region density gradient and diffusion force on the majority
carriers exist.
6. At equilibrium, the diffusion force is balanced by the electric force on the
carriers.
7. No voltage applied to the junction– P-N junction at thermal equilibrium
This is called ZERO BIASING.
Majority carriers from both side experience a POTENTIAL BARRIER due to
the electric field at the junction.
This barrier at the junction is called BUILT-IN-POTENTIAL BARRIER.
BUILT-IN-POTENTIAL BARRIER ( Vbi) maintains equilibrium between the
carriers across the junction and prevents further recombination across the
junction.
Vbi is calculated as it can not be measured directly.
In the depletion layer, n=0 and p=0
FERMI LEVEL is constant throughout the system.
A bending of band observed from P to N side.
8.
9.
10. Built- in – potential at the P-N junction is given by ,
As
11. Nd and Na will denote the net donor and
acceptor concentrations in the individual
n and p regions, respectively
As lower Ec means a higher voltage, the N
side is at a higher voltage or electrical
potential than the P side.
Similarly,
14. Now P-N junction is in non-equilibrium
Fermi level will no longer be constant
Fermi level on N-side move downward and on P-side move up.
Hence barrier potential Vbi increases, total potential is (Vbi+ VR)
Due to external supply an electric field acts from N- to P-side, which is
same as the depletion layer field
Hence electric field in the depletion layer increases
As electric lines originate from positive charge and ends on negative
charge, the no of charges on either side of the junction also increases,
increasing the depletion layer or SCR width.
Hence no current across the junction
However, small current flows due to minority carriers
16. Breakdown Mechanism:
Breakdown occurs by two mechanisms.
• Avalanche Breakdown
Energetic carriers ionize host atoms and there is carrier
multiplication leading to breakdown.
• Zener Breakdown
Electrons from p-region can tunnel to the conduction
band in the n-region causing breakdown.
17. Avalanche Breakdown : in high electric field
• Electrons or holes traveling inside
the SCR attain high velocity when
reverse bias is high and collide with
atoms dislodging an electron from
the atom and causing an electron-
hole pair to form, the process
continues.
• This is known as Avalanche
multiplication, resulting in a large
reverse bias current leading to
breakdown
np pn
p n
SCR
e-
e-h+
e-h+
e-h+
18. Zener Breakdown : Heavily doped junction
• the valence band edge of p-region will
be at a higher potential than the
conduction band edge of the n-region.
Due to heavy doping depletion layer
will be thin.
• Breakdown occurs due to electron
tunneling between the valence band
of the p-region and conduction band
of the n-region. A large reverse current
flows. This is known as Zener
Breakdown.
Ec
Ev
Ef
Ec
Ef
Ev
p-region
n-region
e-
h +
19. FORWARD BIAS PN JUNCTION
Injection of holes into the n region means these holes are minority carriers
there.
Injection of electrons into the p-region means these electrons are minority
carriers there.
The behavior of these minority carriers is described by the ambipolar
transport equations.
20. Forward Biasing
The applied forward biasing potential Va reduces the depletion layer
potential to (Vbi-Va).
Since the applied field is in the opposite direction now the net EF is
reduced , so thermal eqbm. is also disturbed.
The electric field force that prevented majority carriers from crossing
the space charge region is reduced.
Majority carrier electrons from the n side are now injected across
the depletion region into the p material, and majority carrier holes
from the p side are injected across the depletion region .
As long as the bias Va is applied, the injection of carriers across the
space charge region continues and a current is created in the pn
junction
27. IDEAL PN JUNCTION CURRENT
both electron and hole current density are in the +x direction.
28. Js is referred to as the reverse saturation
current density
29. Ideal reverse saturation current density Js , is a function of the
thermal-equilibrium minority carrier concentrations np0 and pn0 , which
are proportional to ni, which is a very strong function of temperature.
Forward-bias current-voltage relation has Js and
As temperature increases, less forward-bias voltage is required
to obtain the same diode current.
If the voltage is constant, the diode current will increase as
temperature increases
Which makes the forward-bias current-voltage relation a function of temperature
Effect of temperature
30. The IV curves of the silicon PN diode shift to lower voltages
with increasing temperature