1
Arulmigu Meenakshi Amman college of Engineering
Vadamavandal-604410.
Prepared by,
V.Umapathy,
Prof./Mech .
Imortant Questions and Answers
PH25C04- Applied Physics (EE) – II
Syllabus
1. Semiconductor Materials: Intrinsic and Extrinsic Semiconductors, Carrier Concentration-
Fermi level, Dependence on carrier-concentration and temperature, Carrier generation and
recombination, Carrier transport: diffusion and drift, Hall Effect, Applications, Metal-
semiconductor junction (Ohmic and Schottky) .
Activities: Determination of Hall coefficient
2. Dielectrics Materials: Dielectric polarization under static fields - electronic, ionic and
dipolar polarizations-internal fields in solid-Clausius-Mossotti equation, Behavior of
dielectrics in alternating fields- Application of dielectrics in transformers Capacitor
materials, Ferro and piezo materials- Complex dielectric permittivity- dipolar relaxation-
dielectric loss, Applications.
Activities: Measurement of Dielectric Constant of different materials
3. Magnetic Materials: Magnetic material parameters, Ferromagnetic materials, Ferrites - Soft
and Hard magnetic materials, GMR sensors, magnetic disk memories, Principle of magnetic
recording, Materials for magnetic data storage.
Activities: Determination of Hysteresis loop for a ferromagnetic material (B-H curve)
4. Advanced Materials: Thermocouple, bimetals, leads soldering and fuses Materials – their
applications.
Activities: Virtual demonstration of working of various types of thermocouples.
S.No. Description
Unit-I
Semiconductor Materials:
, 2
Introduction
Introduction
Semiconductors are materials with electrical conductivity between that of conductors and insulators.
They're the backbone of modern electronics, used in everything from smartphones to solar panels.
Silicon (Si) is the most common semiconductor material.
Intrinsic Semiconductors
- Pure semiconductor material (no impurities)
- Equal number of electrons (n) and holes (p)
- Examples: pure Si, Ge
- Fermi level (E_F) is mid-gap
- Conductivity is low
Extrinsic Semiconductors
- Doped with impurities (donors or acceptors)
- n-type: donors add extra electrons (n > p)
- p-type: acceptors create extra holes (p > n)
- Increases conductivity significantly
Carrier Concentration
- n = Nc exp(-(Ec - EF)/kT) for electrons
- p = Nv exp(-(EF – Ev)/kT) for holes
- ni² = np (intrinsic carrier concentration)
Fermi Level (EF)
- Energy level with 50% probability of occupancy
- Shifts with doping:
- n-type: E_F moves closer to conduction band
- p-type: E_F moves closer to valence band
Dependence on Temperature
- Carrier concentration increases with temperature
- More electrons jump to conduction band
- Conductivity increases
Carrier Generation & Recombination
- Generation: electron-hole pair creation (thermal, optical)
- Recombination: electron-hole annihilation (direct, indirect)
, 3
Carrier Transport
- Drift: movement due to electric field (current = σE)
- Diffusion: movement from high to low concentration
Hall Effect
- Voltage generated perpendicular to current and magnetic field
- Used to determine:
- Carrier type (n or p)
- Carrier concentration
- Mobility
Applications
- Diodes, transistors, solar cells
- Integrated circuits, sensors, LEDs
Metal-Semiconductor Junction
- Ohmic: linear I-V, low resistance (contacts)
- Schottky: rectifying, barrier (diodes)
Basic Concepts
Basics Concepts- Semiconductors: materials with conductivity between conductors and insulators
- Examples: Silicon (Si), Germanium (Ge)
- Crucial for electronics
Intrinsic Semiconductors
- Pure semiconductors (no impurities)
- Equal electrons (n) and holes (p)
- Fermi level (E_F): mid-gap
- Low conductivity
Extrinsic Semiconductors
- Doped with impurities
- n-type: donors add electrons (n > p)
- p-type: acceptors add holes (p > n)
- Increases conductivity
Carrier Concentration- n = Nc exp(-(Ec - EF)/kT)
- p = Nv exp(-(EF – Ev)/kT)
- ni² = np (intrinsic carrier concentration)
, 4
Fermi Level (EF)
- Energy level with 50% occupancy
- Shifts with doping
Dependence on Temperature
- Carrier concentration increases with temperature
- Conductivity increases
Carrier Generation & Recombination
- Generation: electron-hole pair creation
- Recombination: electron-hole annihilation
Carrier Transport
- Drift: electric field-driven
- Diffusion: concentration gradient-driven
Hall Effect
- Voltage generated perpendicular to current and magnetic field
- Determines carrier type and concentration
Applications
- Diodes, transistors, solar cells
- Integrated circuits, sensors
Metal-Semiconductor Junction
- Ohmic: linear I-V, low resistance
- Schottky: rectifying, barrier
Want more details or specific topics?
Some points to note:
- Doping controls conductivity
- Fermi level is crucial
Two Marks QA
1. What are intrinsic and extrinsic semiconductors?
Intrinsic: pure semiconductor; Extrinsic: doped semiconductor
2. Define Fermi level.
Energy level with 50% probability of occupancy
Arulmigu Meenakshi Amman college of Engineering
Vadamavandal-604410.
Prepared by,
V.Umapathy,
Prof./Mech .
Imortant Questions and Answers
PH25C04- Applied Physics (EE) – II
Syllabus
1. Semiconductor Materials: Intrinsic and Extrinsic Semiconductors, Carrier Concentration-
Fermi level, Dependence on carrier-concentration and temperature, Carrier generation and
recombination, Carrier transport: diffusion and drift, Hall Effect, Applications, Metal-
semiconductor junction (Ohmic and Schottky) .
Activities: Determination of Hall coefficient
2. Dielectrics Materials: Dielectric polarization under static fields - electronic, ionic and
dipolar polarizations-internal fields in solid-Clausius-Mossotti equation, Behavior of
dielectrics in alternating fields- Application of dielectrics in transformers Capacitor
materials, Ferro and piezo materials- Complex dielectric permittivity- dipolar relaxation-
dielectric loss, Applications.
Activities: Measurement of Dielectric Constant of different materials
3. Magnetic Materials: Magnetic material parameters, Ferromagnetic materials, Ferrites - Soft
and Hard magnetic materials, GMR sensors, magnetic disk memories, Principle of magnetic
recording, Materials for magnetic data storage.
Activities: Determination of Hysteresis loop for a ferromagnetic material (B-H curve)
4. Advanced Materials: Thermocouple, bimetals, leads soldering and fuses Materials – their
applications.
Activities: Virtual demonstration of working of various types of thermocouples.
S.No. Description
Unit-I
Semiconductor Materials:
, 2
Introduction
Introduction
Semiconductors are materials with electrical conductivity between that of conductors and insulators.
They're the backbone of modern electronics, used in everything from smartphones to solar panels.
Silicon (Si) is the most common semiconductor material.
Intrinsic Semiconductors
- Pure semiconductor material (no impurities)
- Equal number of electrons (n) and holes (p)
- Examples: pure Si, Ge
- Fermi level (E_F) is mid-gap
- Conductivity is low
Extrinsic Semiconductors
- Doped with impurities (donors or acceptors)
- n-type: donors add extra electrons (n > p)
- p-type: acceptors create extra holes (p > n)
- Increases conductivity significantly
Carrier Concentration
- n = Nc exp(-(Ec - EF)/kT) for electrons
- p = Nv exp(-(EF – Ev)/kT) for holes
- ni² = np (intrinsic carrier concentration)
Fermi Level (EF)
- Energy level with 50% probability of occupancy
- Shifts with doping:
- n-type: E_F moves closer to conduction band
- p-type: E_F moves closer to valence band
Dependence on Temperature
- Carrier concentration increases with temperature
- More electrons jump to conduction band
- Conductivity increases
Carrier Generation & Recombination
- Generation: electron-hole pair creation (thermal, optical)
- Recombination: electron-hole annihilation (direct, indirect)
, 3
Carrier Transport
- Drift: movement due to electric field (current = σE)
- Diffusion: movement from high to low concentration
Hall Effect
- Voltage generated perpendicular to current and magnetic field
- Used to determine:
- Carrier type (n or p)
- Carrier concentration
- Mobility
Applications
- Diodes, transistors, solar cells
- Integrated circuits, sensors, LEDs
Metal-Semiconductor Junction
- Ohmic: linear I-V, low resistance (contacts)
- Schottky: rectifying, barrier (diodes)
Basic Concepts
Basics Concepts- Semiconductors: materials with conductivity between conductors and insulators
- Examples: Silicon (Si), Germanium (Ge)
- Crucial for electronics
Intrinsic Semiconductors
- Pure semiconductors (no impurities)
- Equal electrons (n) and holes (p)
- Fermi level (E_F): mid-gap
- Low conductivity
Extrinsic Semiconductors
- Doped with impurities
- n-type: donors add electrons (n > p)
- p-type: acceptors add holes (p > n)
- Increases conductivity
Carrier Concentration- n = Nc exp(-(Ec - EF)/kT)
- p = Nv exp(-(EF – Ev)/kT)
- ni² = np (intrinsic carrier concentration)
, 4
Fermi Level (EF)
- Energy level with 50% occupancy
- Shifts with doping
Dependence on Temperature
- Carrier concentration increases with temperature
- Conductivity increases
Carrier Generation & Recombination
- Generation: electron-hole pair creation
- Recombination: electron-hole annihilation
Carrier Transport
- Drift: electric field-driven
- Diffusion: concentration gradient-driven
Hall Effect
- Voltage generated perpendicular to current and magnetic field
- Determines carrier type and concentration
Applications
- Diodes, transistors, solar cells
- Integrated circuits, sensors
Metal-Semiconductor Junction
- Ohmic: linear I-V, low resistance
- Schottky: rectifying, barrier
Want more details or specific topics?
Some points to note:
- Doping controls conductivity
- Fermi level is crucial
Two Marks QA
1. What are intrinsic and extrinsic semiconductors?
Intrinsic: pure semiconductor; Extrinsic: doped semiconductor
2. Define Fermi level.
Energy level with 50% probability of occupancy
