This document discusses the electronic structure of solids and semiconductors. It explains how the discrete energy levels in isolated atoms become energy bands as atoms approach each other in solids. Semiconductors have a small bandgap that can be bridged by thermal excitation, making them partially conductive. Doping semiconductors with impurities creates excess electrons or holes, making them n-type or p-type. The p-n junction forms a diode with rectifying properties due to a built-in electric field at the junction. Bipolar transistors use a pair of merged p-n junctions to amplify signals.
Derive the thermal-equilibrium concentrations of electrons and holes in a semiconductor as a function of the Fermi energy level.
Discuss the process by which the properties of a semiconductor material can be favorably altered by adding specific impurity atoms to the semiconductor.
Determine the thermal-equilibrium concentrations of electrons and holes in a semiconductor as a function of the concentration of dopant atoms added to the semiconductor.
Determine the position of the Fermi energy level as a function of the concentrations of dopant atoms added to the semiconductor.
Derive the thermal-equilibrium concentrations of electrons and holes in a semiconductor as a function of the Fermi energy level.
Discuss the process by which the properties of a semiconductor material can be favorably altered by adding specific impurity atoms to the semiconductor.
Determine the thermal-equilibrium concentrations of electrons and holes in a semiconductor as a function of the concentration of dopant atoms added to the semiconductor.
Determine the position of the Fermi energy level as a function of the concentrations of dopant atoms added to the semiconductor.
Conectando Turismo e Viagens - Plataforma WSO2Edgar Silva
Entenda como podemos apoiar na inovação da indústria de turismo, viagem, lazer e loyalty com alguns conceitos chave para seus negócios dos próximos 5 anos.
Ransomware is a creative malware that infects systems and locks down data, preventing users from accessing it until a ransom is paid. The data is more or less lost, unless backups are available. So in these types of threats, it is better to focus on prevention and detection mechanisms before it is too late.
Basics of Band Structure and semiconductors.pdfDr Biplab Bag
Basics of Band Structure and semiconductors: How the energy bands and energy gaps are formed, Classification of metals/insulators/semiconductors, Fermi level, conduction & valance bands have been discussed
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Forklift Classes Overview by Intella PartsIntella Parts
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Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
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Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
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COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
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My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
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Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
Courier management system project report.pdfKamal Acharya
It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
1. Bohr quantized the atom…
An atom has a set of energy levels
Some (but not all) occupied by
electrons
Not really dealing with isolated
atoms, but 3D solids
As atoms approach each other, each
affects the other
Energy levels are altered, splitting into
bands
Each atom in the system produces
another energy level in the band
structure
2. Broadening of energy
levels as atoms approach
Degenerate: All electrons
in an orbital have the same
(lowest) energy
Electronic structure of Solids
Electronenergy
gas
Outer levels begin to interact
Overlapping levels
4. Immediate implication for X-Ray microanalysis…
Electron transitions from split levels (bands) will result in
photon emission energies that do not reflect the discrete
degenerate level…
5. Conduction band:
First empty band above
the highest filled band
Valence band:
Outermost band
containing electrons
nucleus
Conduction
band
Valence band
Outermost
band
containing
elelectrons
Electron
energy
Bandgap
Bandgap
Bandgap
Partially full
Full
Full
Empty band
6. Transitions from the
valence band involved
in characteristic X-ray
emission will be energy
shifted depending on
bond lengths, etc.
Resulting X-Rays will
not be monochromatic
These will be Kα X-rays
for ultra-light elements nucleus
Conduction
band
Valence band
Electron
energy
Bandgap
Partially full
Empty band
N=1 (K)
N=2 (L)
8. Insulators:
Valence band full or nearly full
Wide band gap with empty
conduction band
Essentially no available energy
states to which electron energies
can be increased
Dielectric breakdown at high potential
Conduction band
Empty
Valence band
Full
Eg Wide bandgap
9. Semiconductors:
Similar to insulators but narrow band gap
At electrical temperatures some electrons can
be promoted to the conduction band
Most are cubic Diamond FCC (single element)
Some common band gaps:
Element gap (ev)
Ge 0.6
Si 1.1
GaAs 1.4
SiO2 9.0
Conduction band
Almost Empty
Valence band
Almost Full
Conduction band
Empty
Valence band
Full
T > 0K T = 0K
Eg bandgap
S
Zn
Mark McClure, UNC-
Pembroke
Zinc blende
(FCC ZnS)
10. Semiconductors are either
intrinsic or extrinsic
Intrinsic Semiconductors: Pure state
Example: Covalently bonded, tetravalent Si lattice
Promotion of an electron to the conduction band leaves “hole” in the
valence band = electron-hole pair
Apply an electric field and the electron will migrate to +
The hole will migrate to – (that is, the electron next to the hole will be
attracted to the +, leaving a hole toward -)
Net propagation of hole
Ec
Ev
Eg
- +
11. Extrinsic Semiconductors:
Doped with impurity atoms
p-type
n-type
n-type
Dope Si with something like pentavalent antimony (5 valence electrons)
Narrows the band gap relative to Si
easy to promote Sb electron
Majority carriers are electrons in conduction band
Minority carriers are holes in valence band
Lattice doped with donor atoms
localized energy levels just below conduction band
13. p-type
Dope Si with something like trivalent indium (3 valence electrons)
Incomplete bonding with Si
Nearby electron from Si can fill hole
Majority carriers are holes in the valence band
Minority carriers are electrons in the conduction band
Lattice doped with acceptor atoms
localized energy levels just above valence band
15. Fermi Level:
That energy level for which there is a 50% probability of
being occupied by an electron
Conduction band
Ec
Ev
Eg
Valence band
Ec
Ev
Eg
Valence band
Conduction band
Ef
Ef
Intrinsic
n-type
Recombination
Electron-hole pairs not long lasting
Electron encountering hole can “fall” into it
Free time = microsecond or less
16. The p-n junction
Single crystal of semiconductor
Make one end p-type (dope with acceptors)
Make the other end n-type (dope with doners)
The junction of the two leads to rectification
Current only passed in one direction (diode)
In the region of the junction
Recombination = depletion of region with few charge carriers
Results in “built-in” electric field
+
+
+
+
+
+
Depletion width W
Space-charge layers
Direction of built-in field
-
-
-
-
-
-
-
p n
17. Energy band diagram for p-n junction at equilibrium
+
+
+
+
+
+
Depletion width W
Space-charge layers
Direction of built-in field
-
-
-
-
-
-
-
p n
Ecp
Evp
Ecn
Evn
Efn
Efp
eV0
Apply eV0 to get diffusion
18. Energy band diagram for p-n junction – applied forward bias
+
+
+
+
+
+
Depletion width W
Space-charge layers
Direction of built-in field
-
-
-
-
-
-
-
p n
Ecp
Evp
Ecn
Evn
Efn
Efp
eV
Apply small V to get diffusion
Depletion width reduced
Built-in field reduced
Barrier height reduced
Diffusion current increased
If Vforward = V0
No barrier
Pass large
current in
one direction
+ -
19. Energy band diagram for p-n junction – applied reverse bias
+
+
+
+
+
+
Depletion width W
Space-charge layers
Direction of built-in field
-
-
-
-
-
-
-
p n
Ecp
Evp
Ecn
Evn
eV
Depletion width increased
Built-in field increased
Barrier height increased - Diffusion current decreased
Becomes
Capacitor
No current
passed
+-
20. So:
Can use reversed bias p-n junction as voltage regulator
Zener diode
Voltage too high? Overcome gap energy and pass current
Can use forward bias p-n junction for rectification
AC → DCtransformer
Analog-to-digital conversion
LED
Recombination – “tune” bandgap to achieve photon emission
at the required wavelength
GaAs (IR) GaInN (blue) GaAsP (red) YAG:Ce (white)
Ternary and quaternary compounds allow precise bandgap engineering
PIN diode (p and n sections separated by high resistance material)
light detection
X-ray detection
electron detection
-Each of these serve to excite electron-hole pairs
-Bias properly and get amplification rather than simple propagation
21. Bipolar transistor = pair of merged diodes - NPN or PNP
N P N P N P
collector emitter collector emitter
base base
Three voltages (NPN)
Collector = + relative to base (collects
electrons)
Emitter = - relative to base (emits electrons)
Small adjustments of the current on the base
results in large changes in collector current.
= current amplifier
Amplify weak signals
Use small currents to
switch large ones
22.
23. Simple optical encoding:
Generate sine wave by LED passing ruled slide
Phototransistor sees varying light intensity
current output varies with base current
Diode rectifies
AC→DC
Square waves
Digital output to counter