Apply Semiconductor Theory
3.1 Explanation of Semiconductor Theory
A semiconductor is a material whose electrical conductivity lies between that of a conductor and
an insulator. Its conductivity can be controlled by adding impurities (doping), temperature
changes, light, or electric fields.
Semiconductor theory explains how electrons and holes move within a material to conduct
electricity and how semiconductor devices such as diodes and transistors operate.
Key Concepts
Valence electrons: Electrons in the outermost shell of an atom.
Free electrons: Electrons that are free to move and conduct current.
Holes: Vacant positions left by electrons, which act as positive charge carriers.
Doping: The process of adding impurities to a semiconductor to improve conductivity.
3.2 Description of Structure of Matter
Matter is composed of tiny particles called atoms.
Structure of an Atom
An atom consists of:
1. Protons – positively charged particles in the nucleus.
2. Neutrons – neutral particles in the nucleus.
3. Electrons – negatively charged particles orbiting the nucleus.
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, Electron Shells
Electrons occupy energy levels or shells around the nucleus.
Example: Silicon has 14 electrons arranged as:
First shell: 2 electrons
Second shell: 8 electrons
Third shell: 4 electrons (valence electrons)
The four valence electrons enable silicon atoms to form covalent bonds with neighboring atoms.
3.3 Explanation of Electrons in Conductors and Semiconductors
Conductors
Examples: Copper, Aluminum, Silver
Characteristics:
Have many free electrons.
Electrons move easily under an applied voltage.
Low resistance.
Semiconductors
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3.1 Explanation of Semiconductor Theory
A semiconductor is a material whose electrical conductivity lies between that of a conductor and
an insulator. Its conductivity can be controlled by adding impurities (doping), temperature
changes, light, or electric fields.
Semiconductor theory explains how electrons and holes move within a material to conduct
electricity and how semiconductor devices such as diodes and transistors operate.
Key Concepts
Valence electrons: Electrons in the outermost shell of an atom.
Free electrons: Electrons that are free to move and conduct current.
Holes: Vacant positions left by electrons, which act as positive charge carriers.
Doping: The process of adding impurities to a semiconductor to improve conductivity.
3.2 Description of Structure of Matter
Matter is composed of tiny particles called atoms.
Structure of an Atom
An atom consists of:
1. Protons – positively charged particles in the nucleus.
2. Neutrons – neutral particles in the nucleus.
3. Electrons – negatively charged particles orbiting the nucleus.
Page 1 of 12
, Electron Shells
Electrons occupy energy levels or shells around the nucleus.
Example: Silicon has 14 electrons arranged as:
First shell: 2 electrons
Second shell: 8 electrons
Third shell: 4 electrons (valence electrons)
The four valence electrons enable silicon atoms to form covalent bonds with neighboring atoms.
3.3 Explanation of Electrons in Conductors and Semiconductors
Conductors
Examples: Copper, Aluminum, Silver
Characteristics:
Have many free electrons.
Electrons move easily under an applied voltage.
Low resistance.
Semiconductors
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