Podcast
Questions and Answers
What is the conductivity range for semiconductors?
What is the conductivity range for semiconductors?
Which characteristic is true for n-type semiconductors?
Which characteristic is true for n-type semiconductors?
What energy gap value range corresponds to semiconductors?
What energy gap value range corresponds to semiconductors?
Which of the following is an example of an intrinsic semiconductor?
Which of the following is an example of an intrinsic semiconductor?
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What occurs during forward biasing of a p-n junction diode?
What occurs during forward biasing of a p-n junction diode?
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Which material exhibits an energy gap of approximately 5.4 eV?
Which material exhibits an energy gap of approximately 5.4 eV?
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What classifies a material as a conductor based on energy bands?
What classifies a material as a conductor based on energy bands?
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What defines the conduction band in a solid?
What defines the conduction band in a solid?
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Study Notes
Classification of Solids
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Conductor: Easily conducts electricity; σ = 102-108 Ω-1m-1; ρ = 10-8-10-2 Ωm
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Semiconductor: Conducts at higher temperatures; σ = 10-5-106 Ω-1m-1; σ increases with temperature
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Insulator: Does not conduct; σ = 10-8-10-10 Ω-1m-1; ρ = 108-1011 Ωm
Classification Based on Energy Bands
- Valance Band (VB): Energy band of valence electrons
- Conduction Band (CB): Energy band of conduction electrons
- Band Gap Energy (Eg): Energy difference between VB and CB; determines the solid's conductivity type
Types of Semiconductors
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Intrinsic Semiconductor: Pure semiconductors; e.g., Ge, Si
- Electrons in CB; Holes in VB
- Eg for Ge = 0.7 eV; Eg for Si = 1.1 eV
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Extrinsic Semiconductor: Impure semiconductors; increased conductivity. Two types:
- N-type: Increased electron concentration; doping with III group elements (e.g., Boron) creates electron-deficient states; major charge carrier: electron (e-)
- P-type: Increased hole concentration; doping with V group elements(e.g., Phosphorus) creates electron-rich states; major charge carrier: hole (h+)
Materials
- Elemental Semiconductors: Ge, Si, etc.
- Compound Semiconductors: CdS, GaAs, CdSe, etc.
- Organic Semiconductors: Anthracene, doped phthalocyanines
- Organic Polymers: Polypyrrole, polyaniline, polythiophene, etc.
Applications
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P-N Junction: Forward bias and reverse bias
- Forward bias: Electron movement from n-type to p-type; Hole movement from p-type to n-type
- Reverse bias: Depletion layer widens; current reduced
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Rectifier (AC to DC): Half-wave, full-wave
- Half wave rectifier: Converts AC to pulsating DC
- Full-wave rectifier: Converts AC to smoother DC
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Description
This quiz covers the classification of solids based on their conductivity types: conductors, semiconductors, and insulators. It also explores the energy band theory, including valence and conduction bands, and the characteristics of intrinsic and extrinsic semiconductors. Test your knowledge on these concepts fundamental to solid-state physics!
