This document contains 18 multiple choice questions regarding semiconductor physics and properties of semiconductors like silicon. The questions cover topics such as carrier mobility, Fermi level occupation probability, drift velocity, minority carrier concentration, intrinsic carrier concentration, doping, and band gaps. The document provides the questions, answers, and short explanations or calculations for each question.
I show how much GW corrections are important not only for the band structure but also in the calculation of the electron-phonon matrix elements. I present different examples and comparison with the experimental results.
Dear Students/Parents
We at 'Apex Institute' are committed to provide our students best quality education with ethics. Moving in this direction, we have decided that unlike other expensive and 5star facility type institutes who are huge investors and advertisers, we shall not invest huge amount of money in advertisements. It shall rather be invested on the betterment, enhancement of quality and resources at our center.
We are just looking forward to have 'word-of-mouth' publicity instead. Because, there is only a satisfied student and his/her parents can judge an institute's quality and it's faculty members coaching.
Those coaching institutes, who are investing highly on advertisements, are actually, wasting their money on it, in a sense. Rather, the money should be invested on highly experienced faculty members and on teaching gears.
We all at 'Apex' are taking this initiative to improve the quality of education along-with each student's development and growth.
Committed to excellence...
With best wishes.
S . Iqbal
( Motivator & Mentor)
I show how much GW corrections are important not only for the band structure but also in the calculation of the electron-phonon matrix elements. I present different examples and comparison with the experimental results.
Dear Students/Parents
We at 'Apex Institute' are committed to provide our students best quality education with ethics. Moving in this direction, we have decided that unlike other expensive and 5star facility type institutes who are huge investors and advertisers, we shall not invest huge amount of money in advertisements. It shall rather be invested on the betterment, enhancement of quality and resources at our center.
We are just looking forward to have 'word-of-mouth' publicity instead. Because, there is only a satisfied student and his/her parents can judge an institute's quality and it's faculty members coaching.
Those coaching institutes, who are investing highly on advertisements, are actually, wasting their money on it, in a sense. Rather, the money should be invested on highly experienced faculty members and on teaching gears.
We all at 'Apex' are taking this initiative to improve the quality of education along-with each student's development and growth.
Committed to excellence...
With best wishes.
S . Iqbal
( Motivator & Mentor)
Dear Students/Parents
We at 'Apex Institute' are committed to provide our students best quality education with ethics. Moving in this direction, we have decided that unlike other expensive and 5star facility type institutes who are huge investors and advertisers, we shall not invest huge amount of money in advertisements. It shall rather be invested on the betterment, enhancement of quality and resources at our center.
We are just looking forward to have 'word-of-mouth' publicity instead. Because, there is only a satisfied student and his/her parents can judge an institute's quality and it's faculty members coaching.
Those coaching institutes, who are investing highly on advertisements, are actually, wasting their money on it, in a sense. Rather, the money should be invested on highly experienced faculty members and on teaching gears.
We all at 'Apex' are taking this initiative to improve the quality of education along-with each student's development and growth.
Committed to excellence...
With best wishes.
S . Iqbal
( Motivator & Mentor)
Tem for incommensurately modulated materialsJoke Hadermann
This presentation is a teaching lecture given on the International School on Aperiodic Crystals and explains how to index electron diffraction patterns taken from incommensurately modulated materials, with exercises, and gives some examples of HAADF-STEM and HRTEM images on incommensurately modulated materials.
Dear Students/Parents
We at 'Apex Institute' are committed to provide our students best quality education with ethics. Moving in this direction, we have decided that unlike other expensive and 5star facility type institutes who are huge investors and advertisers, we shall not invest huge amount of money in advertisements. It shall rather be invested on the betterment, enhancement of quality and resources at our center.
We are just looking forward to have 'word-of-mouth' publicity instead. Because, there is only a satisfied student and his/her parents can judge an institute's quality and it's faculty members coaching.
Those coaching institutes, who are investing highly on advertisements, are actually, wasting their money on it, in a sense. Rather, the money should be invested on highly experienced faculty members and on teaching gears.
We all at 'Apex' are taking this initiative to improve the quality of education along-with each student's development and growth.
Committed to excellence...
With best wishes.
S . Iqbal
( Motivator & Mentor)
ICC has developed these training modules in order to help people understand the science behind cool roofing and heat transfer management within buildings.
We at 'Apex Institute' are committed to provide our students best quality education with ethics. Moving in this direction, we have decided that unlike other expensive and 5star facility type institutes who are huge investors and advertisers, we shall not invest huge amount of money in advertisements. It shall rather be invested on the betterment, enhancement of quality and resources at our center.
We are just looking forward to have 'word-of-mouth' publicity instead. Because, there is only a satisfied student and his/her parents can judge an institute's quality and it's faculty members coaching.
Those coaching institutes, who are investing highly on advertisements, are actually, wasting their money on it, in a sense. Rather, the money should be invested on highly experienced faculty members and on teaching gears.
We all at 'Apex' are taking this initiative to improve the quality of education along-with each student's development and growth.
Committed to excellence...
With best wishes.
S . Iqbal
( Motivator & Mentor)
Prof Tom Trainor (University of Washington, Seattle, USA)Rene Kotze
TITLE: Two cultures in high energy nuclear physics
Since the mid eighties a community originating within the Bevalac program at the LBNL has sought to achieve formation of a color-deconfined quark-gluon plasma in heavy ion (A-A) collisions using successively higher collision energies at the AGS, SPS, RHIC and now the LHC, emphasizing a flowing dense "partonic" medium as the principal phenomenon. During much of the same period the high energy physics (HEP) community studying elementary collisions (e-e, e-p, p-p) developed the modern theory of QCD, emphasizing dijet production (fragmentation of scattered partons to observable hadrons) as the principal (calculable) phenomenon. Initially it was assumed that the QGP phenomenon in most-central A-A collisions might be distinguished from the HEP dijet phenomenon in elementary collisions. However, strong overlaps in phenomenology have revealed significant conflicts between QGP and HEP "cultures," especially at RHIC and LHC energies. In this talk I review some of the history and contrast an assortment of experimental evidence and interpretations from the two cultures with suggested conflict resolution.
Scheelite CGEW/MO for luminescence - Summary of the paperJoke Hadermann
This presentation gives very shortly the highlights of our paper.
Incommensurate Modulation and Luminescence in the CaGd2(1-x)Eu2x(MoO4)(4(1-y))(WO4)(4y) (0 <=><=><=><= 1) Red Phosphors
published in Chemistry of Materials, 25, 21 (2013) 4387-4395
by Vladimir Morozov, Anne Bertha, Katrien Meert, Senne Van Rompaey, Dmitry Batuk, Gerardo T. Martinez, Sandra Van Aert, Philippe F. Smet, Maria Raskina, Dirk Poelman, Artem Abakumov, Joke Hadermann
Dear Students/Parents
We at 'Apex Institute' are committed to provide our students best quality education with ethics. Moving in this direction, we have decided that unlike other expensive and 5star facility type institutes who are huge investors and advertisers, we shall not invest huge amount of money in advertisements. It shall rather be invested on the betterment, enhancement of quality and resources at our center.
We are just looking forward to have 'word-of-mouth' publicity instead. Because, there is only a satisfied student and his/her parents can judge an institute's quality and it's faculty members coaching.
Those coaching institutes, who are investing highly on advertisements, are actually, wasting their money on it, in a sense. Rather, the money should be invested on highly experienced faculty members and on teaching gears.
We all at 'Apex' are taking this initiative to improve the quality of education along-with each student's development and growth.
Committed to excellence...
With best wishes.
S . Iqbal
( Motivator & Mentor)
conceptual-problems-in-physics-for-iit-jee (1)APEX INSTITUTE
APEX INSTITUTE was conceptualized in May 2008, keeping in view the dreams of young students by the vision & toil of Er. Shahid Iqbal. We had a very humble beginning as an institute for IIT-JEE / Medical, with a vision to provide an ideal launch pad for serious JEE students . We actually started to make a difference in the way students think and approach problems. We started to develop ways to enhance students IQ. We started to leave an indelible mark on the students who have undergone APEX training. That is why APEX INSTITUTE is very well known of its quality of education and the dedication towards its target.
EFFECT OF ELECTRON-PHONON INTERACTION ON ELECTRON SPIN POLARIZATION IN A QUAN...optljjournal
This paper presents a theoretical model for the effect of electron-phonon interaction, temperature and magnetic field on degree of electron spin polarization in GaAs/InAs quantum dot LED. To describe the dynamics, quantum Langevin equation for photon number and carrier number is used. Simulation results show that degree of electron spin polarization in quantum dot decreases with increase of electron phonon interaction parameter at constant temperature and constant magnetic field which agrees with experimental results in literatures.
Quantum chemical molecular dynamics simulations of graphene hydrogenationStephan Irle
Chemical adsorption of hydrogen atoms on graphite
surfaces has attracted considerable interest due to its
relevance for a broad range of areas including
plasma/fusion physics, gap tuning in graphene, and hydrogen storage. We adjusted the C-H repulsive potential of the spin-polarized self-consistent-charge density-functional tight-binding (sSCC-DFTB) method to reproduce
CCSD(T)-based relaxed potential energy curves for the
attack of atomic hydrogen on a center carbon atom of
pyrene and coronene at a tiny fraction of the computational
cost. Using this cheap quantum chemical potential, we performed direct on-the-fly Born-Oppenheimer
MD simulations while “shooting” H atoms with varying collision energies on a periodic graphene target
equilibrated at 300 Kelvin. We compared reaction cross sections for a) elastic collisions, b)
chemisorption reactions, c) penetration reactions in dependence of H/D/T kinetic energies, and found
remarkable differences to previously reported classical MD simulations of the same process. Using the
same potential, in simulations involving the shooting of up to 400 hydrogen atoms on the graphene sheet,
we observed the self-assembly of C4H, a novel polymer with localized aromatic hexagons, in agreement
with recent experimental findings.
Dear Students/Parents
We at 'Apex Institute' are committed to provide our students best quality education with ethics. Moving in this direction, we have decided that unlike other expensive and 5star facility type institutes who are huge investors and advertisers, we shall not invest huge amount of money in advertisements. It shall rather be invested on the betterment, enhancement of quality and resources at our center.
We are just looking forward to have 'word-of-mouth' publicity instead. Because, there is only a satisfied student and his/her parents can judge an institute's quality and it's faculty members coaching.
Those coaching institutes, who are investing highly on advertisements, are actually, wasting their money on it, in a sense. Rather, the money should be invested on highly experienced faculty members and on teaching gears.
We all at 'Apex' are taking this initiative to improve the quality of education along-with each student's development and growth.
Committed to excellence...
With best wishes.
S . Iqbal
( Motivator & Mentor)
Tem for incommensurately modulated materialsJoke Hadermann
This presentation is a teaching lecture given on the International School on Aperiodic Crystals and explains how to index electron diffraction patterns taken from incommensurately modulated materials, with exercises, and gives some examples of HAADF-STEM and HRTEM images on incommensurately modulated materials.
Dear Students/Parents
We at 'Apex Institute' are committed to provide our students best quality education with ethics. Moving in this direction, we have decided that unlike other expensive and 5star facility type institutes who are huge investors and advertisers, we shall not invest huge amount of money in advertisements. It shall rather be invested on the betterment, enhancement of quality and resources at our center.
We are just looking forward to have 'word-of-mouth' publicity instead. Because, there is only a satisfied student and his/her parents can judge an institute's quality and it's faculty members coaching.
Those coaching institutes, who are investing highly on advertisements, are actually, wasting their money on it, in a sense. Rather, the money should be invested on highly experienced faculty members and on teaching gears.
We all at 'Apex' are taking this initiative to improve the quality of education along-with each student's development and growth.
Committed to excellence...
With best wishes.
S . Iqbal
( Motivator & Mentor)
ICC has developed these training modules in order to help people understand the science behind cool roofing and heat transfer management within buildings.
We at 'Apex Institute' are committed to provide our students best quality education with ethics. Moving in this direction, we have decided that unlike other expensive and 5star facility type institutes who are huge investors and advertisers, we shall not invest huge amount of money in advertisements. It shall rather be invested on the betterment, enhancement of quality and resources at our center.
We are just looking forward to have 'word-of-mouth' publicity instead. Because, there is only a satisfied student and his/her parents can judge an institute's quality and it's faculty members coaching.
Those coaching institutes, who are investing highly on advertisements, are actually, wasting their money on it, in a sense. Rather, the money should be invested on highly experienced faculty members and on teaching gears.
We all at 'Apex' are taking this initiative to improve the quality of education along-with each student's development and growth.
Committed to excellence...
With best wishes.
S . Iqbal
( Motivator & Mentor)
Prof Tom Trainor (University of Washington, Seattle, USA)Rene Kotze
TITLE: Two cultures in high energy nuclear physics
Since the mid eighties a community originating within the Bevalac program at the LBNL has sought to achieve formation of a color-deconfined quark-gluon plasma in heavy ion (A-A) collisions using successively higher collision energies at the AGS, SPS, RHIC and now the LHC, emphasizing a flowing dense "partonic" medium as the principal phenomenon. During much of the same period the high energy physics (HEP) community studying elementary collisions (e-e, e-p, p-p) developed the modern theory of QCD, emphasizing dijet production (fragmentation of scattered partons to observable hadrons) as the principal (calculable) phenomenon. Initially it was assumed that the QGP phenomenon in most-central A-A collisions might be distinguished from the HEP dijet phenomenon in elementary collisions. However, strong overlaps in phenomenology have revealed significant conflicts between QGP and HEP "cultures," especially at RHIC and LHC energies. In this talk I review some of the history and contrast an assortment of experimental evidence and interpretations from the two cultures with suggested conflict resolution.
Scheelite CGEW/MO for luminescence - Summary of the paperJoke Hadermann
This presentation gives very shortly the highlights of our paper.
Incommensurate Modulation and Luminescence in the CaGd2(1-x)Eu2x(MoO4)(4(1-y))(WO4)(4y) (0 <=><=><=><= 1) Red Phosphors
published in Chemistry of Materials, 25, 21 (2013) 4387-4395
by Vladimir Morozov, Anne Bertha, Katrien Meert, Senne Van Rompaey, Dmitry Batuk, Gerardo T. Martinez, Sandra Van Aert, Philippe F. Smet, Maria Raskina, Dirk Poelman, Artem Abakumov, Joke Hadermann
Dear Students/Parents
We at 'Apex Institute' are committed to provide our students best quality education with ethics. Moving in this direction, we have decided that unlike other expensive and 5star facility type institutes who are huge investors and advertisers, we shall not invest huge amount of money in advertisements. It shall rather be invested on the betterment, enhancement of quality and resources at our center.
We are just looking forward to have 'word-of-mouth' publicity instead. Because, there is only a satisfied student and his/her parents can judge an institute's quality and it's faculty members coaching.
Those coaching institutes, who are investing highly on advertisements, are actually, wasting their money on it, in a sense. Rather, the money should be invested on highly experienced faculty members and on teaching gears.
We all at 'Apex' are taking this initiative to improve the quality of education along-with each student's development and growth.
Committed to excellence...
With best wishes.
S . Iqbal
( Motivator & Mentor)
conceptual-problems-in-physics-for-iit-jee (1)APEX INSTITUTE
APEX INSTITUTE was conceptualized in May 2008, keeping in view the dreams of young students by the vision & toil of Er. Shahid Iqbal. We had a very humble beginning as an institute for IIT-JEE / Medical, with a vision to provide an ideal launch pad for serious JEE students . We actually started to make a difference in the way students think and approach problems. We started to develop ways to enhance students IQ. We started to leave an indelible mark on the students who have undergone APEX training. That is why APEX INSTITUTE is very well known of its quality of education and the dedication towards its target.
EFFECT OF ELECTRON-PHONON INTERACTION ON ELECTRON SPIN POLARIZATION IN A QUAN...optljjournal
This paper presents a theoretical model for the effect of electron-phonon interaction, temperature and magnetic field on degree of electron spin polarization in GaAs/InAs quantum dot LED. To describe the dynamics, quantum Langevin equation for photon number and carrier number is used. Simulation results show that degree of electron spin polarization in quantum dot decreases with increase of electron phonon interaction parameter at constant temperature and constant magnetic field which agrees with experimental results in literatures.
Quantum chemical molecular dynamics simulations of graphene hydrogenationStephan Irle
Chemical adsorption of hydrogen atoms on graphite
surfaces has attracted considerable interest due to its
relevance for a broad range of areas including
plasma/fusion physics, gap tuning in graphene, and hydrogen storage. We adjusted the C-H repulsive potential of the spin-polarized self-consistent-charge density-functional tight-binding (sSCC-DFTB) method to reproduce
CCSD(T)-based relaxed potential energy curves for the
attack of atomic hydrogen on a center carbon atom of
pyrene and coronene at a tiny fraction of the computational
cost. Using this cheap quantum chemical potential, we performed direct on-the-fly Born-Oppenheimer
MD simulations while “shooting” H atoms with varying collision energies on a periodic graphene target
equilibrated at 300 Kelvin. We compared reaction cross sections for a) elastic collisions, b)
chemisorption reactions, c) penetration reactions in dependence of H/D/T kinetic energies, and found
remarkable differences to previously reported classical MD simulations of the same process. Using the
same potential, in simulations involving the shooting of up to 400 hydrogen atoms on the graphene sheet,
we observed the self-assembly of C4H, a novel polymer with localized aromatic hexagons, in agreement
with recent experimental findings.
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
Kubernetes & AI - Beauty and the Beast !?! @KCD Istanbul 2024Tobias Schneck
As AI technology is pushing into IT I was wondering myself, as an “infrastructure container kubernetes guy”, how get this fancy AI technology get managed from an infrastructure operational view? Is it possible to apply our lovely cloud native principals as well? What benefit’s both technologies could bring to each other?
Let me take this questions and provide you a short journey through existing deployment models and use cases for AI software. On practical examples, we discuss what cloud/on-premise strategy we may need for applying it to our own infrastructure to get it to work from an enterprise perspective. I want to give an overview about infrastructure requirements and technologies, what could be beneficial or limiting your AI use cases in an enterprise environment. An interactive Demo will give you some insides, what approaches I got already working for real.
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
Accelerate your Kubernetes clusters with Varnish CachingThijs Feryn
A presentation about the usage and availability of Varnish on Kubernetes. This talk explores the capabilities of Varnish caching and shows how to use the Varnish Helm chart to deploy it to Kubernetes.
This presentation was delivered at K8SUG Singapore. See https://feryn.eu/presentations/accelerate-your-kubernetes-clusters-with-varnish-caching-k8sug-singapore-28-2024 for more details.
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
Connector Corner: Automate dynamic content and events by pushing a buttonDianaGray10
Here is something new! In our next Connector Corner webinar, we will demonstrate how you can use a single workflow to:
Create a campaign using Mailchimp with merge tags/fields
Send an interactive Slack channel message (using buttons)
Have the message received by managers and peers along with a test email for review
But there’s more:
In a second workflow supporting the same use case, you’ll see:
Your campaign sent to target colleagues for approval
If the “Approve” button is clicked, a Jira/Zendesk ticket is created for the marketing design team
But—if the “Reject” button is pushed, colleagues will be alerted via Slack message
Join us to learn more about this new, human-in-the-loop capability, brought to you by Integration Service connectors.
And...
Speakers:
Akshay Agnihotri, Product Manager
Charlie Greenberg, Host
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
1. Semiconductor Physics – GATE Problems
1. A P-type silicon sample has higher conductivity compared to an n-type
silicon sample having the same dopant concentration. TRUE/FALSE
[GATE 1994: 1 Mark]
Soln. For a given semiconductor the electron mobility (𝝁 𝒏) is always higher
than hole mobility (𝝁 𝒑).
Typical values are
For 𝑺𝒊, 𝝁 𝒏 = 𝟏𝟑𝟓𝟎 𝒄𝒎 𝟐
/𝒗 − 𝒔𝒆𝒄.
𝝁 𝒑 = 𝟒𝟖𝟎 𝒄𝒎 𝟐
/𝒗 − 𝒔𝒆𝒄.
𝑻𝒉𝒖𝒔 , 𝝁 𝒏 > 𝝁 𝒑
Electron conductivity, 𝝈 𝒏 = 𝒏𝒒 𝝁 𝒏
Hole conductivity, 𝝈 𝒑 = 𝒑𝒒 𝝁 𝒑
Since, n = p (Dopant concentration is same)
q is same for both
thus 𝝈 𝒏 > 𝝈 𝒑
Ans False
2. The Probability that an electron in a metal occupies the Fermi level, at
any temperature. (> 0K)
(a) 0
(b)1
(c) 0.5
(d)1.0
[GATE 1995: 1 Mark]
Soln. In metal: The probability that an electron occupies Fermi level for
T>0 is 1 (since conduction and valence bands are overlapping in
metals).
In Insulator: The probability that electron occupies the Fermi level is
0.5
(Since there is small band gap in semiconductors)
Option (c)
2. 3. The drift velocity of electrons in silicon
(a) is proportional to the electric field for all values of electric field
(b)is independent of the electric field
(c) increases at low values of electric field and decreases at high values of
electric field exhibiting negative differential resistance
(d)increases linearly with electric field and gradually saturates at higher
values of electric field
[GATE 1995: 1 Mark]
Soln. Drift velocity is proportional to electric filed.
𝒗 𝒅 ∝ 𝑬
𝒗 𝒅𝒏 = 𝝁 𝒏 𝑬
(Drift velocity for electrons)
Where 𝝁 𝒏 =
𝒒𝝉 𝒄
𝒎 𝒏
Where 𝝉 𝒄 average time between collisions.
𝑣 𝑑
E
For Si
For small values of E, 𝝁 𝒏 remains constant and drift velocity is
proportional to E. But when E becomes very high the drift velocity
saturates as shown in the given Figure
Thus option (d)
3. 4. In a P-type Si sample the hole concentration is2.25 × 1015
/𝑐𝑚3
. The
intrinsic carrier Concentration is 1.5 × 1010
/𝑐𝑚3
the electron
concentration is
(a) Zero
(b)1010
/𝑐𝑚3
(c) 105
/𝑐𝑚3
(d)1.5 × 1025
/𝑐𝑚3
[GATE 1995: 1 Mark]
Soln. In this problem the hole concentration is given and intrinsic carrier
concertation is given, we have to find electron concentration. We
apply mass action law
𝒏. 𝒑 = 𝒏𝒊
𝟐
Given , 𝒑 = 𝟐. 𝟐𝟓 × 𝟏𝟎 𝟏𝟓
/𝒄𝒎 𝟑
𝒏𝒊 = 𝟏. 𝟓 × 𝟏𝟎 𝟏𝟎
/𝒄𝒎 𝟑
So,
𝒏 =
𝒏𝒊
𝟐
𝒑
=
(𝟏. 𝟓 × 𝟏𝟎 𝟏𝟎) 𝟐
𝟐. 𝟐𝟓 × 𝟏𝟎 𝟏𝟓
=
𝟐. 𝟐𝟓 × 𝟏𝟎 𝟐𝟎
𝟐. 𝟐𝟓 × 𝟏𝟓 𝟏𝟓
= 𝟏𝟎 𝟓
/𝒄𝒎 𝟑
Option (c)
5. A small concentration of minority carries is injected into a homogeneous
Semiconductor crystal at one point. An electric field of 10V/cm is applied
across the crystal and this moves the minority carries a distance of 1 cm
in 20 µ sec. The mobility (in cm2
/v-sec) will be
(a) 1,000
(b)2,000
(c) 5,000
(d)500,000
[GATE 1994: 1 Mark]
Soln. Given:
Electric field 𝟏𝟎 𝑽 𝒄𝒎⁄
Distance moved by minority carrier 1 cm.
4. Time taken 20 µ sec.
So, the velocity of minority
𝐂𝐚𝐫𝐫𝐢𝐞𝐫 =
𝑫𝒊𝒔𝒕𝒂𝒏𝒄𝒆 𝒎𝒐𝒗𝒆𝒅
𝒕𝒊𝒎𝒆 𝒕𝒂𝒌𝒆𝒏
=
𝟏 𝒄𝒎
𝟐𝟎×𝟏𝟎−𝟔 = 𝟓𝟎, 𝟎𝟎𝟎 𝒄𝒎/𝒔𝒆𝒄
Drift velocity (𝒗 𝒅) = 𝝁 𝑬
𝒐𝒓, 𝝁 =
𝒗 𝒅
𝑬
=
𝟓𝟎,𝟎𝟎
𝟏𝟎
𝒐𝒓, 𝝁 = 𝟓𝟎𝟎𝟎𝒄𝒎 𝟐
/𝒗 − 𝒔
Option (c)
6. The units of
𝑞
𝐾𝑇
are
(a) V
(b) 𝑉−1
(c) J
(d)J/K
[GATE 1997: 1 Mark]
Soln. To find the units of
𝒒
𝒌𝑻
Unit of k (Boltzmann constant) J/K
Unit of q - Coulomb
Since the options (c) and (d) are not appropriate and the other two
options are in volt
So,
𝒒
𝒌𝑻
=
𝑪
𝑱/𝑲×𝑲
=
𝑪
𝑱
We know unit of volt is
𝟏 𝑱𝒐𝒖𝒍𝒆/𝑪𝒐𝒖𝒍𝒐𝒎𝒃
So, unit of
𝒒
𝒌𝑻
=
𝟏
𝑱/𝑪
=
𝟏
𝑽
= 𝑽−𝟏
Alternative We know
𝒌𝑻
𝒒
= 𝟐𝟔 𝒎𝑽
So unit of
𝒒
𝒌𝑻
= 𝟏/𝑽 = 𝑽−𝟏
Option (b)
5. 7. The intrinsic carrier concentration of silicon sample at 3000
K is
1.5 × 1016
/𝑚3
. If after doping, the number of majority carriers is
5 × 1020
/𝑚3
, the minority carrier density is
(a) 4.50 × 1011
/𝑚3
(b)3.33 × 104
/𝑚3
(c) 5.00 × 1020
/𝑚3
(d)3.00 × 10−5
/𝑚3
[GATE 2002: 1 Mark]
Soln. Given,
𝒏𝒊 = 𝟏. 𝟓 × 𝟏𝟎 𝟏𝟔
/𝒎 𝟑
𝒏 = 𝟓 × 𝟏𝟎 𝟐𝟎
/𝒎 𝟑
Note that concentrations are given in m3
not in cm3
.
𝒑 =
𝒏𝒊
𝟐
𝒏
=
(𝟏. 𝟓 × 𝟏𝟔 𝟏𝟔) 𝟐
𝟓 × 𝟏𝟎 𝟐𝟎
=
𝟐. 𝟐𝟓 × 𝟏𝟎 𝟑𝟐
𝟓 × 𝟏𝟎 𝟐𝟎
= 𝟒𝟓 × 𝟏𝟎 𝟏𝟎
= 𝟒. 𝟓 × 𝟏𝟎 𝟏𝟏
Option (a)
8. The band gap of silicon at 300 K is
(a) 1.36 eV
(b)1.10 eV
(c) 0.80 eV
(d)0.67 eV
[GATE 2002: 1 Mark]
Soln. There are standard values of the band gaps at room temp (300 K)
𝑺𝒊 𝟏. 𝟏 𝒆𝒗
𝑮 𝒆 𝟎. 𝟕 𝒆𝒗
GaAs 𝟏. 𝟒𝟏 𝒆𝒗
Option (b)
9. n – type silicon is obtained by doping silicon with
6. (a) Germanium
(b)Aluminum
(c) Boron
(d)Phosphorus
[GATE 2003: 1 Mark]
Soln. For n – type doped silicon pentavalent impurities are added such as
Antimony, Arsenic or Phosphorus so out of given option the correct
option is (d)
10. The impurity commonly used for realizing the base region of a silicon
n-p-n transistor is
(a) Gallium
(b)Indium
(c) Boron
(d)Phosphorus
[GATE 2004: 1 Mark]
Soln. The base region of n-p-n transistor is p type for p – type material the
impurities of trivalent type added such as Boron, Gallium or Indium
In the present problem Boron is correct choice
Option (c)
11. The primary reason for the wide spread use of silicon in semiconductor
device technology is
(a) Abundance of silicon on the surface of the Earth.
(b)Larger bandgap of silicon in comparison to germanium.
(c) Favorable properties of silicon – dioxide (𝑠𝑖𝑜2)
(d)Lower melting point.
[GATE 2004: 1 Mark]
Soln. In this problem various options are given and we have to find the
primary reason. Option (a) that silicon is available in abundance is
correct option. Option (b) larger bandgap of SiType equation here. in
comparison to Ge is also true. Option (c) the favorable properties of
Silicon – dioxide (Si02) is also right. Option (d) is not right. So out of
three options which are correct the primary reason is option (a).
Since, Silicon is available in sand which is in abundance so, option (a)
is the primary reason.
12. A silicon PN junction at a temperature of 200
C has a reverse saturation
current of 10pA. The reverse saturation current at 400
C for the same bias
is approximately.
7. (a) 20 pA
(b)30 pA
(c) 40 pA
(d)80 pA
[GATE 2004: 1 Mark]
Soln. We know that for Silicon PN junction every 10℃ rise in temperature,
reverse saturation current doubles.
At 20℃ reverse saturation is 10 pA.
At 30℃ reverse saturation current will be 20 pA
At 40℃ reverse saturation will be 40 pA
Option (C)
13. The band gap of silicon at room temperature is
(a) 1.3 eV
(b)0.7 eV
(c) 1.1 eV
(d)1.4 eV
[GATE 2005: 1 Mark]
Soln. Band gaps for the commonly used semiconductors are
Si - 1.1eV
Ge - 0.7eV
GaAs - 1.4eV
So, for Si the value is 1.1eV
Option (c)
14. Under low level injection assumption, the injected minority carrier
current for an extrinsic semiconductor is essentially the
(a) Diffusion current
(b)Drift current
(c) Recombination current
(d)Induced current
[GATE 2005: 1 Mark]
Soln. Total current density is given by
𝑱 𝒏 = 𝒒𝒖 𝝁 𝒏 𝑬 + 𝒒 𝑫 𝒏
𝒅𝒏
𝒅𝒙
8. The first term represents the drift current due to electric field (E)
and second term represents diffusion current due to concentration
gradient.
Because there is low level injection so n is small. First term will give
negligible current. Here
𝒅𝒏
𝒅𝒙
is not small.
So the current will be due to diffusion current term.
Option (a)
15. The concentration of minority carriers in an extrinsic semiconductor
under equilibrium is
(a) Directly proportional to the doping concentration.
(b)Inversely proportional to the doping concentration.
(c) Directly proportional to the intrinsic concentration.
(d)Inversely proportional to the intrinsic concentration.
[GATE 2006: 1 Mark]
Soln. For n type semiconductor p (holes) represents the minority carrier
concentration.
As per Mass Action law
𝒏. 𝒑 = 𝒏𝒊
𝟐
= 𝒄𝒐𝒏𝒔𝒕𝒂𝒏𝒕
So 𝒑 ∝
𝟏
𝒏
So, inversely proportional to doping concentration
Option (b)
16. The electron and hole concentration in an intrinsic semiconductor are ni
per cm3
at 3000
K. Now, if acceptor impurities are concentration of NA
per cm3
at 3000
K with be
(a) 𝑛𝑖
(b)ni + NA
(c) NA − ni
(d)
𝑛 𝑖
2
𝑁 𝐴
[GATE 2007: 1 Mark]
Soln. As per law of mass action
9. 𝒏. 𝒑 = 𝒏𝒊
𝟐
Where,
n – free election concertation
p – hole concentration
ni – intrinsic carrier concentration
Acceptor impurity NA is hole concentration (p)
So, Electron concentration (𝒏) =
𝒏 𝒊
𝟐
𝑵 𝑨
Option (d)
17. Which of the following is true?
(a) A silicon wafer heavily doped with boron is a P +
substrate.
(b)A silicon wafer lightly doped with boron is a P +
substrate.
(c) A silicon wafer heavily doped with arsenic is a P +
substrate.
(d)A silicon wafer lightly doped with arsenic is a P +
substrate.
[GATE 2008: 1 Mark]
Soln. Trivalent impurities such as Boron, Gallium or Indium
Are used to make P – type semiconductor
Thus, silicon wafer heavily doped with Boron in a P+ substrate.
Option (a)
18. In an n – type silicon crystal at room temperature, which of the following
can have a concentration of4 × 1019
/𝑐𝑚3
?
(a) Silicon atoms
(b)Holes
(c) Dopant atoms
(d)Valence electrons
[GATE 2009: 1 Mark]
10. Soln. We should remember the order of concentrations for intrinsic and
doped semiconductor. Intrinsic carrier concentration is of the order
of ≅ 𝟏. 𝟓 × 𝟏𝟎 𝟏𝟎
/𝒄𝒎 𝟑
Doped semiconductor concentration is ≅ 𝟐 × 𝟏𝟎 𝟏𝟓
/𝒄𝒎 𝟑
The given concentration is
𝟒 × 𝟏𝟎 𝟏𝟗
𝒄𝒎−𝟑
This means it is the concentration of dopant atoms, since it is more
than ≅ 𝟏𝟎 𝟏𝟓
𝒄𝒎−𝟑
Option (c)
19. Drift current in semiconductors depends upon
(a) Only the electric field
(b)Only the carrier concentration gradient
(c) Both the electric field and the carrier concentration
(d)Neither the electric field nor the carrier concentration gradient
[GATE 2011: 1 Mark]
Soln. Drift current is given by
𝑰 𝒅 = 𝒏𝒒 𝝁 𝒏 𝑬.
From above relation we observe that drift current depends on
Electric filed and carrier concentration
Option (c)
20. A silicon bar is doped with donor impurities 𝑁 𝐷 = 2.25 × 1015
𝑎𝑡𝑜𝑚𝑠/
𝑐𝑚3
. Given the intrinsic carrier concentration of silicon at T = 300 K is
𝑛𝑖 = 1.5 × 1010
𝑐𝑚−3
. Assuming complete impurity ionization, the
equilibrium electron and hole concentrations are
(a) 𝑛0 = 1.5 × 1016
𝑐𝑚−3
, 𝑝0 = 1.5 × 105
𝑐𝑚−3
(b) 𝑛0 = 1.5 × 1010
𝑐𝑚−3
, 𝑝0 = 1.5 × 1015
𝑐𝑚−3
(c) 𝑛0 = 2.25 × 1015
𝑐𝑚−3
, 𝑝0 = 1.5 × 1010
𝑐𝑚−3
(d) 𝑛0 = 2.25 × 1015
𝑐𝑚−3
, 𝑝0 = 1 × 105
𝑐𝑚−3
[GATE 2014: 1 Mark]
Soln. Given,
11. Donor impurities, 𝑵 𝑫 = 𝟐. 𝟐𝟓 × 𝟏𝟎 𝟏𝟓
𝒂𝒕𝒐𝒎/𝒄𝒎 𝟑
when there is
complete impurity ionization the number of electrons provided will
be the same as Donor impurities. i.e.
𝒏 = 𝑵 𝑫 = 𝟐. 𝟐𝟓 × 𝟏𝟎 𝟏𝟓
/𝒄𝒎 𝟑
𝑷 𝟎 =
𝒏𝒊
𝟐
𝒏 𝟎
=
(𝟏. 𝟓 × 𝟏𝟎 𝟏𝟎) 𝟐
𝟐. 𝟐𝟓 × 𝟏𝟓 𝟏𝟓
=
𝟐. 𝟐𝟓 × 𝟏𝟎 𝟐𝟎
𝟐. 𝟐𝟓 × 𝟏𝟎 𝟏𝟓
= 𝟏𝟎 𝟓
/𝒄𝒎 𝟑
Option (d)
21. A thin P – type silicon sample is uniformly illuminated with light which
generates excess carriers. The recombination rate is directly proportional
to
(a) The minority carrier mobility
(b)The minority carrier recombination lifetime
(c) The majority carrier concentration
(d)The excess minority carrier concentration
[GATE 2014: 1 Mark]
Soln. A P – type sample is illuminated with light,that generates exces
carriers.
Here majority carriers are holes since sample is of P – type.
When light falls on the sample minority carriers will be generated. As
the minority carrier concentration increases probability of
recombination increase.
Option (d)
22. At T = 300 K, the hole mobility of a semiconductor 𝜇 𝑝 = 500 𝑐𝑚2
/𝑉 −
𝑠 and
𝑘𝑇
𝑞
= 26𝑚𝑉. The hole diffusion constant 𝐷 𝑝 𝑖𝑛 𝑐𝑚2
/𝑠 is
[GATE 2014: 1 Mark]
Soln. Given,
At T = 300K
12. Hoe mobility (𝝁 𝒑) = 𝟓𝟎𝟎 𝒄𝒎 𝟐
/𝑽 − 𝑺
𝒌𝑻
𝒒
= 𝟐𝟔 𝒎𝒗
Find hole diffusion constant .Einstein equation relates diffusivity and
mobility the two important constants through the relation
𝑫 𝑷 = (
𝒌𝑻
𝒒
) 𝝁 𝑷
So, 𝑫 𝑷 = 𝝁 𝑷 . 𝑽 𝑻
𝑫 𝑷 = 𝟓𝟎𝟎 × 𝟐𝟔 × 𝟏𝟎−𝟑
𝒐𝒓, 𝑫 𝑷 = 𝟏𝟑𝒄𝒎 𝟐
/𝑺
Ans 𝟏𝟑𝒄𝒎 𝟐
/𝑺
23. In the figure, 𝑙 𝑛(𝑝𝑖) is plotted as function of 1/T, where pi is the intrinsic
resistivity of silicon, T is the temperature, and the plot is almost linear.
𝑰 𝒏(𝝆𝒊)
1/T
The slope of the line can be used to estimate
(a) Band gap energy of silicon (Eg)
(b)Sum of electron and hole mobility in silicon (𝜇 𝑛 + 𝜇 𝑝)
(c) Reciprocal of the sum of electron and hole mobility in silicon
(𝜇 𝑛 + 𝜇 𝑝)
−1
(d)Intrinsic carrier concentration of silicon (ni)
[GATE 2014: 1 Mark]
13. Soln. The given plot is between 𝒍 𝒏(𝝆𝒊) 𝒂𝒏𝒅 𝟏 𝑻⁄ .
As temperature (T) increases Energy gap Eg decreases Due to
decrease in Eg electron hole pair generation increase. So conductivity
(𝝈) increases. This can be represented is short as
At 𝑻 ↑→ 𝑬 𝒈 ↓→ (𝒏 𝒂𝒏𝒅 𝒑) ↑→ 𝝈 ↑ 𝝆 ↓
So in short As 𝑻 ↑→ 𝝆𝒊 ↓
or As
𝟏
𝑻
↑→ 𝝆𝒊 ↑→ 𝒍 𝒏(𝝆𝒊) ↑
Plot is linear
So the slope can be used to determine the band gap (Eg)
The book of S.M. Sze contains the plot of intrinsic carrier densities
for Si and GaAs as 1/T
The larger the band gap the smaller the intrinsic carrier density.
Here, option (a)
24. A silicon sample is uniformly doped with donor type impurities with a
concertation of 1016
/𝑐𝑚3
.
The electron and hole mobility’s in the sample are 1200𝑐𝑚2
/𝑉 − 𝑠 and
400 𝑐𝑚2
/𝑉 − 𝑠 respectively
Assume complete ionization of impurities.
The charge of an electron is 1.6 × 10−19
𝐶. The resistivity of the sample
𝑖𝑛 Ω − 𝑐𝑚 is --------.
Soln. Given,
Donor impurity concentration = 𝟏𝟎 𝟏𝟔
/𝒄𝒎 𝟑
𝝁 𝒏 = 𝟏𝟐𝟎𝟎 𝒄𝒎 𝟐
/𝑽
𝝁 𝒑 = 𝟒𝟎𝟎 𝒄𝒎 𝟐
/𝑽
Conductivity
𝝈 𝑵 = 𝑵 𝑫 𝒒 𝝁 𝒏
= 𝟏𝟎 𝟏𝟔
× 𝟏. 𝟔 × 𝟏𝟎−𝟏𝟗
× 𝟏𝟐𝟎𝟎
= 𝟏. 𝟗𝟐 ʊ /𝒄𝒎
14. So, Resistivity
𝝆 =
𝟏
𝝈 𝑵
=
𝟏
𝟏.𝟗𝟐
Or, 𝝆 = 𝟎. 𝟓𝟐 𝛀 − 𝒄𝒎
25. A piece of silicon is doped uniformly with phosphorous with a doping
concentration of 1016
/𝑐𝑚3
. The expected value of mobility versus
doping concentration for silicon assuming full dopant ionization is shown
below. The charge of an electron is 1.6 × 10−19
𝐶. The conductivity (in S
cm-1
) of the silicon sample at 300 K is
Soln. Given,
Si is doped with phosphorus with doping concentration of 𝟏𝟎 𝟏𝟔
/𝒄𝒎 𝟑
(N type)
Plot is given for hole and electron mobility at 300K.
Conductivity (𝝈 𝑵) = 𝑵 𝑫 𝒒 𝝁 𝒑
We find the value of 𝝁 𝑷 for electron for concentration of 𝟏𝟎 𝟏𝟔
/𝒄𝒎 𝟑
.
The value is 𝝁 𝒏 = 𝟏𝟐𝟎𝟎𝒄𝒎 𝟐
/𝑽 − 𝑺
So, 𝝈 𝑵 = 𝟏𝟎 𝟔
× 𝟏. 𝟔 × 𝟏𝟎−𝟏𝟗
× 𝟏𝟐𝟎𝟎 = 𝟏. 𝟗𝟐 𝑺𝒊𝒆𝒎𝒆𝒏𝒔/𝒄𝒎
Ans 1.92 S/cm