SlideShare une entreprise Scribd logo
1  sur  21
Télécharger pour lire hors ligne
Metal Semi
Conductor Junctions
Agha Muqaddas Ali Khan MESP-1501
Asad Ali MESP-1517
Contents
Introduction
Metals
Semiconductors
Metal Semiconductor Junctions
Schottky Barriers
Rectifying Contacts
Ohmic Contacts
Typical Schottky Barriers
Introduction
Metals
• Good electrical conductors
• Free electrons
• Overlapping C.B. and V.B.
• Fermi level at center of
C.B. and V.B.
Semiconductors
• Intermediate conductivity
• Narrow band gap
• Either Electrons or Holes
as Majority Charge Carriers
• Fermi Level can be shifted
EF
ElectronEnergy
Band
Overlapping
Conduction Band
Valence Band
Metal
ElectronEnergy
Eg
Valence Band
Conduction Band
EF
Intrinsic Semiconductor
Metal Semi Conductor Junction
Need for Metal SC Junction
• As metal contacts
• To connect external
circuitry with the device
Semiconductor
Device
Junction formation b/w
metal contact and SC
Effect of Metal SC Junction
• Variation in Device
Behavior
• Control May lost
V
Schottky Barrier
Metal and N-Type SC
Φ 𝑚 = Work fn. Of Metal
Φ 𝑠 = Work fn. Of SC
Φ 𝑚 > Φ 𝑠
𝑞χ =Electron Affinity
Schottky Barrier
Formation Of Junction
 Fermi level aligning at equilibrium
 Creation of Contact Potential= 𝑉𝑜
 𝑉𝑜 = Φ 𝑚 − Φ 𝑠
 Potential Barrier For electron
injection= Φ 𝐵
 Φ 𝐵 = Φ 𝑚 − χ
 This barrier is called Schottky
Barrier
Schottky Barrier
Metal and P-Type SC
Φ 𝑚 = Work fn. Of Metal
Φ 𝑠 = Work fn. Of SC
Φ 𝑚 < Φ 𝑠
𝑞χ =Electron Affinity
Schottky Barrier
Fermi level aligning at
equilibrium
Creation of Contact
Potential= 𝑉𝑜
𝑉𝑜 = Φ 𝑠 − Φ 𝑚
Potential Barrier For electron
injection= Φ 𝐵
𝑞Φ 𝐵
Formation Of Junction
Rectifying Contacts
• Forward Biasing Schottky
Barrier
• 𝑉𝑜 𝑉𝑜 − 𝑉
• Electron Diff. becomes
easier from SC to M
• Here it is behaving like a
F.B pn junction diode.
F.B. Schottky Barrier
Rectifying Contacts
R.B. Schottky Barrier
• Reverse Biasing Schottky
Barrier
• 𝑽 𝒐 𝑽 𝒐 + 𝑽
• Electron flow from SC to M
becomes Negligible
• Here it is behaving like a R.B
PN junction diode.
• Electron flow from M to SC is
retarded due to barrier
𝜱 𝒎 − 𝝌 in both cases
Rectifying Contacts
• The resulting diode equation of
Schottky diode is similar to that
form of p-n junction.
𝐼 = 𝐼 𝑜(𝑒
𝑞𝑣
𝑘𝑇 − 1)
• Resulting 𝐼 − 𝑉 curve is similar to a
pn junction diode
• In Schottky diode, the reverse
saturation current depends only on
the size of barrier Φ 𝐵
Ohmic Contacts
The current and voltage must be
proportional:
• Having I-V characteristic must be
linear in both direction- Low
Resistance.
• IC contains thousands of P-N which
must be connected or interconnected
for Proper use of Device.
Ideal MS Contact
Assumptions:
• M and S are in intimate
contact, on atomic scale
• No oxides or charges at the
interface
• No intermixing at the
interface
Ohmic MS Contacts
Ways to achieve Ohmic MS contacts
• Reduce the Schottky barrier height. How???
• Reduce the Schottky barrier width (depletion width). How?
How would each approach give us an ohmic contact?
M-S will be Ohmic
• Ohmic contact occur when the induced
charge in the semiconductor during the
fermi level alignment is the Majority
carriers.
When M < S:
• Fermi level aligned at equilibrium by transforming
electrons from metal to semi conductor.
When M < S:
• Barrier for carriers is small
and easily overcome by a
small voltage.
• No depletion region occur in
the semiconductor since
Fermi level calls for
accumulation of majority
carriers in the semi
conductors
• Ohmic contact are formed by
doping the semiconductor
heavily
When M > S:
• Easy flow of holes across the junction
• No depletion region occur in these region
Practical Ohmic contact
In practice most M-S are rectifying
To achieve the contact which can conduct on both
directions we doped the semiconductor heavily.
 W is so narrow that carrier can tunnel through the
barrier.
Flow of charge by Tunneling
• Narrow space charge region will make more
tunneling effect and small applied voltage is
required
Flow of charge by Tunneling
Typical Schottky barrier
• Surface state leads to charge metal-semiconductor interference.
These surface states often lies in the semiconductor band gap and
pin the Fermi level at the fixed position regardless of the metal
used.
Fermilevelpinningbyinterference states incompoundssemiconductors
𝐸𝑓 pinned near 𝐸𝑐-0.8evinn-typeGaAs,regardlessofthechoiceofmetal.

Contenu connexe

Tendances

Metal semiconductor contact
Metal semiconductor contactMetal semiconductor contact
Metal semiconductor contactAnchit Biswas
 
Semiconductor devices
Semiconductor devicesSemiconductor devices
Semiconductor devicesGS Virdi
 
Schottky diode working and applications
Schottky diode working and applicationsSchottky diode working and applications
Schottky diode working and applicationselprocus
 
Band theory of solids
Band theory of solidsBand theory of solids
Band theory of solidsutpal sarkar
 
Semiconductor diode
Semiconductor diodeSemiconductor diode
Semiconductor diodeRAMPRAKASHT1
 
Band theory of solid
Band theory of solidBand theory of solid
Band theory of solidKeyur Patel
 
Direct and in direct band gap-Modern Physics
Direct and in direct band gap-Modern PhysicsDirect and in direct band gap-Modern Physics
Direct and in direct band gap-Modern PhysicsChandra Prakash Pandey
 
Chapter5 carrier transport phenomena
Chapter5 carrier transport phenomenaChapter5 carrier transport phenomena
Chapter5 carrier transport phenomenaK. M.
 
Energy band theory of solids
Energy band theory of solidsEnergy band theory of solids
Energy band theory of solidsBarani Tharan
 
Semiconductor Devices
Semiconductor DevicesSemiconductor Devices
Semiconductor DevicesRajesh Kumar
 

Tendances (20)

Mosfet
MosfetMosfet
Mosfet
 
Metal semiconductor contact
Metal semiconductor contactMetal semiconductor contact
Metal semiconductor contact
 
PN JUNCTION
PN JUNCTION PN JUNCTION
PN JUNCTION
 
Semiconductor devices
Semiconductor devicesSemiconductor devices
Semiconductor devices
 
Mosfet
MosfetMosfet
Mosfet
 
Mosfet
MosfetMosfet
Mosfet
 
Energy bands insolids
Energy bands insolidsEnergy bands insolids
Energy bands insolids
 
Schottky diode working and applications
Schottky diode working and applicationsSchottky diode working and applications
Schottky diode working and applications
 
Hetero junction
Hetero junctionHetero junction
Hetero junction
 
Semiconductor diodes
Semiconductor diodesSemiconductor diodes
Semiconductor diodes
 
Band theory of solids
Band theory of solidsBand theory of solids
Band theory of solids
 
Semiconductor diode
Semiconductor diodeSemiconductor diode
Semiconductor diode
 
Semiconductors
SemiconductorsSemiconductors
Semiconductors
 
Band theory of solid
Band theory of solidBand theory of solid
Band theory of solid
 
MS Junction
MS JunctionMS Junction
MS Junction
 
Pn junction diode
Pn junction diodePn junction diode
Pn junction diode
 
Direct and in direct band gap-Modern Physics
Direct and in direct band gap-Modern PhysicsDirect and in direct band gap-Modern Physics
Direct and in direct band gap-Modern Physics
 
Chapter5 carrier transport phenomena
Chapter5 carrier transport phenomenaChapter5 carrier transport phenomena
Chapter5 carrier transport phenomena
 
Energy band theory of solids
Energy band theory of solidsEnergy band theory of solids
Energy band theory of solids
 
Semiconductor Devices
Semiconductor DevicesSemiconductor Devices
Semiconductor Devices
 

En vedette

Lecture 4 4521 semiconductor device physics - metal-semiconductor system
Lecture 4   4521 semiconductor device physics - metal-semiconductor systemLecture 4   4521 semiconductor device physics - metal-semiconductor system
Lecture 4 4521 semiconductor device physics - metal-semiconductor systemNedal Al Taradeh
 
Ete411 Lec14
Ete411 Lec14Ete411 Lec14
Ete411 Lec14mashiur
 
43 sabrina l. lee - 5956604 - ohmic contact to gallium arsenide using epita...
43   sabrina l. lee - 5956604 - ohmic contact to gallium arsenide using epita...43   sabrina l. lee - 5956604 - ohmic contact to gallium arsenide using epita...
43 sabrina l. lee - 5956604 - ohmic contact to gallium arsenide using epita...Mello_Patent_Registry
 
Theory discussion
Theory discussionTheory discussion
Theory discussionRay Wang
 
Presentation on metal junction
Presentation  on metal junctionPresentation  on metal junction
Presentation on metal junctionSashank Patodia
 
High concentration photovoltaics: potentials and challenges
High concentration photovoltaics: potentials and challengesHigh concentration photovoltaics: potentials and challenges
High concentration photovoltaics: potentials and challengesLeonardo ENERGY
 
Seebeck effect & peltier effect
Seebeck effect & peltier effectSeebeck effect & peltier effect
Seebeck effect & peltier effectvishal chaturani
 
semiconductor physics,unit 5
semiconductor physics,unit 5semiconductor physics,unit 5
semiconductor physics,unit 5Kumar
 
Diagramas de fase
Diagramas de faseDiagramas de fase
Diagramas de faseIncopin
 
Basic electronics and electrical first year engineering
Basic electronics and electrical first year engineeringBasic electronics and electrical first year engineering
Basic electronics and electrical first year engineeringron181295
 
Voltage regulator
Voltage regulatorVoltage regulator
Voltage regulatorniiraz
 

En vedette (17)

Lecture 4 4521 semiconductor device physics - metal-semiconductor system
Lecture 4   4521 semiconductor device physics - metal-semiconductor systemLecture 4   4521 semiconductor device physics - metal-semiconductor system
Lecture 4 4521 semiconductor device physics - metal-semiconductor system
 
Ete411 Lec14
Ete411 Lec14Ete411 Lec14
Ete411 Lec14
 
43 sabrina l. lee - 5956604 - ohmic contact to gallium arsenide using epita...
43   sabrina l. lee - 5956604 - ohmic contact to gallium arsenide using epita...43   sabrina l. lee - 5956604 - ohmic contact to gallium arsenide using epita...
43 sabrina l. lee - 5956604 - ohmic contact to gallium arsenide using epita...
 
Theory discussion
Theory discussionTheory discussion
Theory discussion
 
Presentation on metal junction
Presentation  on metal junctionPresentation  on metal junction
Presentation on metal junction
 
High concentration photovoltaics: potentials and challenges
High concentration photovoltaics: potentials and challengesHigh concentration photovoltaics: potentials and challenges
High concentration photovoltaics: potentials and challenges
 
Lecture 5: Junctions
Lecture 5: JunctionsLecture 5: Junctions
Lecture 5: Junctions
 
Diodes
DiodesDiodes
Diodes
 
Seebeck effect & peltier effect
Seebeck effect & peltier effectSeebeck effect & peltier effect
Seebeck effect & peltier effect
 
semiconductor physics,unit 5
semiconductor physics,unit 5semiconductor physics,unit 5
semiconductor physics,unit 5
 
Diagramas de fase
Diagramas de faseDiagramas de fase
Diagramas de fase
 
thermocouple ppt
thermocouple pptthermocouple ppt
thermocouple ppt
 
Thermocouple
ThermocoupleThermocouple
Thermocouple
 
Light Dependent Resistor
Light Dependent ResistorLight Dependent Resistor
Light Dependent Resistor
 
Basic electronics and electrical first year engineering
Basic electronics and electrical first year engineeringBasic electronics and electrical first year engineering
Basic electronics and electrical first year engineering
 
Voltage regulator
Voltage regulatorVoltage regulator
Voltage regulator
 
Semiconductor physics
Semiconductor physicsSemiconductor physics
Semiconductor physics
 

Similaire à Metal Semi-Conductor Junctions

Classification of solid using energy level.pptx
Classification of solid using energy level.pptxClassification of solid using energy level.pptx
Classification of solid using energy level.pptxatulnarkhede7
 
Fundamentals of Semiconductor Devices
Fundamentals of Semiconductor DevicesFundamentals of Semiconductor Devices
Fundamentals of Semiconductor DevicesSenthil Kumar
 
BEEIE UNIT IV PPT.ppt
BEEIE UNIT IV PPT.pptBEEIE UNIT IV PPT.ppt
BEEIE UNIT IV PPT.pptDEEBIKAR2
 
BE UNIT 1 PPT.ppt
BE UNIT 1 PPT.pptBE UNIT 1 PPT.ppt
BE UNIT 1 PPT.pptashok kumar
 
Chapter 5 - MOSFET - SEMICONDUCTOR DEVICES.pptx
Chapter 5 - MOSFET - SEMICONDUCTOR DEVICES.pptxChapter 5 - MOSFET - SEMICONDUCTOR DEVICES.pptx
Chapter 5 - MOSFET - SEMICONDUCTOR DEVICES.pptxfarahhanani22
 
schottky barrier and contact resistance
schottky barrier and contact resistanceschottky barrier and contact resistance
schottky barrier and contact resistancepaneliya sagar
 
Electrical Measurements for Semiconducting Devices
Electrical Measurements for Semiconducting DevicesElectrical Measurements for Semiconducting Devices
Electrical Measurements for Semiconducting DevicesYogesh Patil
 
EST 130, Semiconductors
EST 130, SemiconductorsEST 130, Semiconductors
EST 130, SemiconductorsCKSunith1
 
Basic Electronics UNIt1 PPT
Basic Electronics UNIt1 PPTBasic Electronics UNIt1 PPT
Basic Electronics UNIt1 PPTPraveen Kunda
 
Class 12 th semiconductor part 3
Class 12 th semiconductor part 3Class 12 th semiconductor part 3
Class 12 th semiconductor part 3Priyanka Jakhar
 

Similaire à Metal Semi-Conductor Junctions (20)

Classification of solid using energy level.pptx
Classification of solid using energy level.pptxClassification of solid using energy level.pptx
Classification of solid using energy level.pptx
 
MOSFET
MOSFETMOSFET
MOSFET
 
Unit-5.pptx
Unit-5.pptxUnit-5.pptx
Unit-5.pptx
 
Introduction to semiconductors
Introduction to  semiconductorsIntroduction to  semiconductors
Introduction to semiconductors
 
Unit 2 semiconductors
Unit 2  semiconductors Unit 2  semiconductors
Unit 2 semiconductors
 
unit-2.pdf
unit-2.pdfunit-2.pdf
unit-2.pdf
 
BEEE.pptx
BEEE.pptxBEEE.pptx
BEEE.pptx
 
lec 5.ppt
lec 5.pptlec 5.ppt
lec 5.ppt
 
Fundamentals of Semiconductor Devices
Fundamentals of Semiconductor DevicesFundamentals of Semiconductor Devices
Fundamentals of Semiconductor Devices
 
BEEIE UNIT IV PPT.ppt
BEEIE UNIT IV PPT.pptBEEIE UNIT IV PPT.ppt
BEEIE UNIT IV PPT.ppt
 
BE UNIT 1 PPT.ppt
BE UNIT 1 PPT.pptBE UNIT 1 PPT.ppt
BE UNIT 1 PPT.ppt
 
Chapter 5 - MOSFET - SEMICONDUCTOR DEVICES.pptx
Chapter 5 - MOSFET - SEMICONDUCTOR DEVICES.pptxChapter 5 - MOSFET - SEMICONDUCTOR DEVICES.pptx
Chapter 5 - MOSFET - SEMICONDUCTOR DEVICES.pptx
 
schottky barrier and contact resistance
schottky barrier and contact resistanceschottky barrier and contact resistance
schottky barrier and contact resistance
 
4 semiconductor electronics
4 semiconductor electronics4 semiconductor electronics
4 semiconductor electronics
 
Electrical Measurements for Semiconducting Devices
Electrical Measurements for Semiconducting DevicesElectrical Measurements for Semiconducting Devices
Electrical Measurements for Semiconducting Devices
 
EST 130, Semiconductors
EST 130, SemiconductorsEST 130, Semiconductors
EST 130, Semiconductors
 
MOS Structure.pptx
MOS Structure.pptxMOS Structure.pptx
MOS Structure.pptx
 
Basic Electronics UNIt1 PPT
Basic Electronics UNIt1 PPTBasic Electronics UNIt1 PPT
Basic Electronics UNIt1 PPT
 
Electrodes.pdf
Electrodes.pdfElectrodes.pdf
Electrodes.pdf
 
Class 12 th semiconductor part 3
Class 12 th semiconductor part 3Class 12 th semiconductor part 3
Class 12 th semiconductor part 3
 

Dernier

Strategies of Urban Morphologyfor Improving Outdoor Thermal Comfort and Susta...
Strategies of Urban Morphologyfor Improving Outdoor Thermal Comfort and Susta...Strategies of Urban Morphologyfor Improving Outdoor Thermal Comfort and Susta...
Strategies of Urban Morphologyfor Improving Outdoor Thermal Comfort and Susta...amrabdallah9
 
me3493 manufacturing technology unit 1 Part A
me3493 manufacturing technology unit 1 Part Ame3493 manufacturing technology unit 1 Part A
me3493 manufacturing technology unit 1 Part Akarthi keyan
 
Quasi-Stochastic Approximation: Algorithm Design Principles with Applications...
Quasi-Stochastic Approximation: Algorithm Design Principles with Applications...Quasi-Stochastic Approximation: Algorithm Design Principles with Applications...
Quasi-Stochastic Approximation: Algorithm Design Principles with Applications...Sean Meyn
 
Graphics Primitives and CG Display Devices
Graphics Primitives and CG Display DevicesGraphics Primitives and CG Display Devices
Graphics Primitives and CG Display DevicesDIPIKA83
 
Engineering Mechanics Chapter 5 Equilibrium of a Rigid Body
Engineering Mechanics  Chapter 5  Equilibrium of a Rigid BodyEngineering Mechanics  Chapter 5  Equilibrium of a Rigid Body
Engineering Mechanics Chapter 5 Equilibrium of a Rigid BodyAhmadHajasad2
 
specification estimation and valuation of a building
specification estimation and valuation of a buildingspecification estimation and valuation of a building
specification estimation and valuation of a buildingswethasekhar5
 
Oracle_PLSQL_basic_tutorial_with_workon_Exercises.ppt
Oracle_PLSQL_basic_tutorial_with_workon_Exercises.pptOracle_PLSQL_basic_tutorial_with_workon_Exercises.ppt
Oracle_PLSQL_basic_tutorial_with_workon_Exercises.pptDheerajKashnyal
 
Technology Features of Apollo HDD Machine, Its Technical Specification with C...
Technology Features of Apollo HDD Machine, Its Technical Specification with C...Technology Features of Apollo HDD Machine, Its Technical Specification with C...
Technology Features of Apollo HDD Machine, Its Technical Specification with C...Apollo Techno Industries Pvt Ltd
 
The relationship between iot and communication technology
The relationship between iot and communication technologyThe relationship between iot and communication technology
The relationship between iot and communication technologyabdulkadirmukarram03
 
Basic Principle of Electrochemical Sensor
Basic Principle of  Electrochemical SensorBasic Principle of  Electrochemical Sensor
Basic Principle of Electrochemical SensorTanvir Moin
 
Renewable Energy & Entrepreneurship Workshop_21Feb2024.pdf
Renewable Energy & Entrepreneurship Workshop_21Feb2024.pdfRenewable Energy & Entrepreneurship Workshop_21Feb2024.pdf
Renewable Energy & Entrepreneurship Workshop_21Feb2024.pdfodunowoeminence2019
 
دليل تجارب الاسفلت المختبرية - Asphalt Experiments Guide Laboratory
دليل تجارب الاسفلت المختبرية - Asphalt Experiments Guide Laboratoryدليل تجارب الاسفلت المختبرية - Asphalt Experiments Guide Laboratory
دليل تجارب الاسفلت المختبرية - Asphalt Experiments Guide LaboratoryBahzad5
 
SATELITE COMMUNICATION UNIT 1 CEC352 REGULATION 2021 PPT BASICS OF SATELITE ....
SATELITE COMMUNICATION UNIT 1 CEC352 REGULATION 2021 PPT BASICS OF SATELITE ....SATELITE COMMUNICATION UNIT 1 CEC352 REGULATION 2021 PPT BASICS OF SATELITE ....
SATELITE COMMUNICATION UNIT 1 CEC352 REGULATION 2021 PPT BASICS OF SATELITE ....santhyamuthu1
 
Popular-NO1 Kala Jadu Expert Specialist In Germany Kala Jadu Expert Specialis...
Popular-NO1 Kala Jadu Expert Specialist In Germany Kala Jadu Expert Specialis...Popular-NO1 Kala Jadu Expert Specialist In Germany Kala Jadu Expert Specialis...
Popular-NO1 Kala Jadu Expert Specialist In Germany Kala Jadu Expert Specialis...Amil baba
 
News web APP using NEWS API for web platform to enhancing user experience
News web APP using NEWS API for web platform to enhancing user experienceNews web APP using NEWS API for web platform to enhancing user experience
News web APP using NEWS API for web platform to enhancing user experienceAkashJha84
 
Design Analysis of Alogorithm 1 ppt 2024.pptx
Design Analysis of Alogorithm 1 ppt 2024.pptxDesign Analysis of Alogorithm 1 ppt 2024.pptx
Design Analysis of Alogorithm 1 ppt 2024.pptxrajesshs31r
 
CSR Managerial Round Questions and answers.pptx
CSR Managerial Round Questions and answers.pptxCSR Managerial Round Questions and answers.pptx
CSR Managerial Round Questions and answers.pptxssusera0771e
 
ChatGPT-and-Generative-AI-Landscape Working of generative ai search
ChatGPT-and-Generative-AI-Landscape Working of generative ai searchChatGPT-and-Generative-AI-Landscape Working of generative ai search
ChatGPT-and-Generative-AI-Landscape Working of generative ai searchrohitcse52
 

Dernier (20)

Strategies of Urban Morphologyfor Improving Outdoor Thermal Comfort and Susta...
Strategies of Urban Morphologyfor Improving Outdoor Thermal Comfort and Susta...Strategies of Urban Morphologyfor Improving Outdoor Thermal Comfort and Susta...
Strategies of Urban Morphologyfor Improving Outdoor Thermal Comfort and Susta...
 
me3493 manufacturing technology unit 1 Part A
me3493 manufacturing technology unit 1 Part Ame3493 manufacturing technology unit 1 Part A
me3493 manufacturing technology unit 1 Part A
 
Quasi-Stochastic Approximation: Algorithm Design Principles with Applications...
Quasi-Stochastic Approximation: Algorithm Design Principles with Applications...Quasi-Stochastic Approximation: Algorithm Design Principles with Applications...
Quasi-Stochastic Approximation: Algorithm Design Principles with Applications...
 
Lecture 2 .pptx
Lecture 2                            .pptxLecture 2                            .pptx
Lecture 2 .pptx
 
Graphics Primitives and CG Display Devices
Graphics Primitives and CG Display DevicesGraphics Primitives and CG Display Devices
Graphics Primitives and CG Display Devices
 
Engineering Mechanics Chapter 5 Equilibrium of a Rigid Body
Engineering Mechanics  Chapter 5  Equilibrium of a Rigid BodyEngineering Mechanics  Chapter 5  Equilibrium of a Rigid Body
Engineering Mechanics Chapter 5 Equilibrium of a Rigid Body
 
specification estimation and valuation of a building
specification estimation and valuation of a buildingspecification estimation and valuation of a building
specification estimation and valuation of a building
 
Oracle_PLSQL_basic_tutorial_with_workon_Exercises.ppt
Oracle_PLSQL_basic_tutorial_with_workon_Exercises.pptOracle_PLSQL_basic_tutorial_with_workon_Exercises.ppt
Oracle_PLSQL_basic_tutorial_with_workon_Exercises.ppt
 
Technology Features of Apollo HDD Machine, Its Technical Specification with C...
Technology Features of Apollo HDD Machine, Its Technical Specification with C...Technology Features of Apollo HDD Machine, Its Technical Specification with C...
Technology Features of Apollo HDD Machine, Its Technical Specification with C...
 
The relationship between iot and communication technology
The relationship between iot and communication technologyThe relationship between iot and communication technology
The relationship between iot and communication technology
 
Basic Principle of Electrochemical Sensor
Basic Principle of  Electrochemical SensorBasic Principle of  Electrochemical Sensor
Basic Principle of Electrochemical Sensor
 
Renewable Energy & Entrepreneurship Workshop_21Feb2024.pdf
Renewable Energy & Entrepreneurship Workshop_21Feb2024.pdfRenewable Energy & Entrepreneurship Workshop_21Feb2024.pdf
Renewable Energy & Entrepreneurship Workshop_21Feb2024.pdf
 
دليل تجارب الاسفلت المختبرية - Asphalt Experiments Guide Laboratory
دليل تجارب الاسفلت المختبرية - Asphalt Experiments Guide Laboratoryدليل تجارب الاسفلت المختبرية - Asphalt Experiments Guide Laboratory
دليل تجارب الاسفلت المختبرية - Asphalt Experiments Guide Laboratory
 
SATELITE COMMUNICATION UNIT 1 CEC352 REGULATION 2021 PPT BASICS OF SATELITE ....
SATELITE COMMUNICATION UNIT 1 CEC352 REGULATION 2021 PPT BASICS OF SATELITE ....SATELITE COMMUNICATION UNIT 1 CEC352 REGULATION 2021 PPT BASICS OF SATELITE ....
SATELITE COMMUNICATION UNIT 1 CEC352 REGULATION 2021 PPT BASICS OF SATELITE ....
 
Popular-NO1 Kala Jadu Expert Specialist In Germany Kala Jadu Expert Specialis...
Popular-NO1 Kala Jadu Expert Specialist In Germany Kala Jadu Expert Specialis...Popular-NO1 Kala Jadu Expert Specialist In Germany Kala Jadu Expert Specialis...
Popular-NO1 Kala Jadu Expert Specialist In Germany Kala Jadu Expert Specialis...
 
News web APP using NEWS API for web platform to enhancing user experience
News web APP using NEWS API for web platform to enhancing user experienceNews web APP using NEWS API for web platform to enhancing user experience
News web APP using NEWS API for web platform to enhancing user experience
 
Design Analysis of Alogorithm 1 ppt 2024.pptx
Design Analysis of Alogorithm 1 ppt 2024.pptxDesign Analysis of Alogorithm 1 ppt 2024.pptx
Design Analysis of Alogorithm 1 ppt 2024.pptx
 
計劃趕得上變化
計劃趕得上變化計劃趕得上變化
計劃趕得上變化
 
CSR Managerial Round Questions and answers.pptx
CSR Managerial Round Questions and answers.pptxCSR Managerial Round Questions and answers.pptx
CSR Managerial Round Questions and answers.pptx
 
ChatGPT-and-Generative-AI-Landscape Working of generative ai search
ChatGPT-and-Generative-AI-Landscape Working of generative ai searchChatGPT-and-Generative-AI-Landscape Working of generative ai search
ChatGPT-and-Generative-AI-Landscape Working of generative ai search
 

Metal Semi-Conductor Junctions

  • 1. Metal Semi Conductor Junctions Agha Muqaddas Ali Khan MESP-1501 Asad Ali MESP-1517
  • 2. Contents Introduction Metals Semiconductors Metal Semiconductor Junctions Schottky Barriers Rectifying Contacts Ohmic Contacts Typical Schottky Barriers
  • 3. Introduction Metals • Good electrical conductors • Free electrons • Overlapping C.B. and V.B. • Fermi level at center of C.B. and V.B. Semiconductors • Intermediate conductivity • Narrow band gap • Either Electrons or Holes as Majority Charge Carriers • Fermi Level can be shifted EF ElectronEnergy Band Overlapping Conduction Band Valence Band Metal ElectronEnergy Eg Valence Band Conduction Band EF Intrinsic Semiconductor
  • 4. Metal Semi Conductor Junction Need for Metal SC Junction • As metal contacts • To connect external circuitry with the device Semiconductor Device Junction formation b/w metal contact and SC Effect of Metal SC Junction • Variation in Device Behavior • Control May lost V
  • 5. Schottky Barrier Metal and N-Type SC Φ 𝑚 = Work fn. Of Metal Φ 𝑠 = Work fn. Of SC Φ 𝑚 > Φ 𝑠 𝑞χ =Electron Affinity
  • 6. Schottky Barrier Formation Of Junction  Fermi level aligning at equilibrium  Creation of Contact Potential= 𝑉𝑜  𝑉𝑜 = Φ 𝑚 − Φ 𝑠  Potential Barrier For electron injection= Φ 𝐵  Φ 𝐵 = Φ 𝑚 − χ  This barrier is called Schottky Barrier
  • 7. Schottky Barrier Metal and P-Type SC Φ 𝑚 = Work fn. Of Metal Φ 𝑠 = Work fn. Of SC Φ 𝑚 < Φ 𝑠 𝑞χ =Electron Affinity
  • 8. Schottky Barrier Fermi level aligning at equilibrium Creation of Contact Potential= 𝑉𝑜 𝑉𝑜 = Φ 𝑠 − Φ 𝑚 Potential Barrier For electron injection= Φ 𝐵 𝑞Φ 𝐵 Formation Of Junction
  • 9. Rectifying Contacts • Forward Biasing Schottky Barrier • 𝑉𝑜 𝑉𝑜 − 𝑉 • Electron Diff. becomes easier from SC to M • Here it is behaving like a F.B pn junction diode. F.B. Schottky Barrier
  • 10. Rectifying Contacts R.B. Schottky Barrier • Reverse Biasing Schottky Barrier • 𝑽 𝒐 𝑽 𝒐 + 𝑽 • Electron flow from SC to M becomes Negligible • Here it is behaving like a R.B PN junction diode. • Electron flow from M to SC is retarded due to barrier 𝜱 𝒎 − 𝝌 in both cases
  • 11. Rectifying Contacts • The resulting diode equation of Schottky diode is similar to that form of p-n junction. 𝐼 = 𝐼 𝑜(𝑒 𝑞𝑣 𝑘𝑇 − 1) • Resulting 𝐼 − 𝑉 curve is similar to a pn junction diode • In Schottky diode, the reverse saturation current depends only on the size of barrier Φ 𝐵
  • 12. Ohmic Contacts The current and voltage must be proportional: • Having I-V characteristic must be linear in both direction- Low Resistance. • IC contains thousands of P-N which must be connected or interconnected for Proper use of Device.
  • 13. Ideal MS Contact Assumptions: • M and S are in intimate contact, on atomic scale • No oxides or charges at the interface • No intermixing at the interface
  • 14. Ohmic MS Contacts Ways to achieve Ohmic MS contacts • Reduce the Schottky barrier height. How??? • Reduce the Schottky barrier width (depletion width). How? How would each approach give us an ohmic contact?
  • 15. M-S will be Ohmic • Ohmic contact occur when the induced charge in the semiconductor during the fermi level alignment is the Majority carriers.
  • 16. When M < S: • Fermi level aligned at equilibrium by transforming electrons from metal to semi conductor.
  • 17. When M < S: • Barrier for carriers is small and easily overcome by a small voltage. • No depletion region occur in the semiconductor since Fermi level calls for accumulation of majority carriers in the semi conductors • Ohmic contact are formed by doping the semiconductor heavily
  • 18. When M > S: • Easy flow of holes across the junction • No depletion region occur in these region
  • 19. Practical Ohmic contact In practice most M-S are rectifying To achieve the contact which can conduct on both directions we doped the semiconductor heavily.  W is so narrow that carrier can tunnel through the barrier.
  • 20. Flow of charge by Tunneling • Narrow space charge region will make more tunneling effect and small applied voltage is required Flow of charge by Tunneling
  • 21. Typical Schottky barrier • Surface state leads to charge metal-semiconductor interference. These surface states often lies in the semiconductor band gap and pin the Fermi level at the fixed position regardless of the metal used. Fermilevelpinningbyinterference states incompoundssemiconductors 𝐸𝑓 pinned near 𝐸𝑐-0.8evinn-typeGaAs,regardlessofthechoiceofmetal.