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Questions and Answers
What type of atoms are introduced into a semiconductor material to create a p-type material?
What is the characteristic of an n-type material?
What happens to the covalent bond when a pentavalent material is added to a semiconductor?
Why are electrons in an n-type material relatively free to move?
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What is the result of introducing impurities into a semiconductor material?
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What type of atoms are used as donor atoms in n-type materials?
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What type of carriers are majority in an n-type material?
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What is the term for the vacancy of electrons in a covalent bond?
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What type of impurities are used to create p-type semiconductor materials?
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What is the result when an electron acquires sufficient energy to break from its covalent bond?
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What is the effect of transfer of electrons and holes in an n-type material?
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What happens to the parent atom when the fifth electron of a donor atom leaves?
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What is the term for the flow of electrons in a material?
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What is the type of semiconductor material resulting from the addition of pentavalent impurities?
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What is the concentration of holes in a p-type silicon material with NA = 1x10^16 atoms/cm^3?
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What is the electron mobility at 300 degrees K?
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What is the concentration of electrons in an intrinsic silicon material at 3000 K?
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What is the effect of adding donor impurity atoms to an intrinsic semiconductor?
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What is the concentration of electrons in an n-type silicon material with ND = 1x10^15 atoms/cm^3?
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What is the relationship between the concentration of free electrons and holes in an extrinsic semiconductor?
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What is the conductivity of an n-type silicon material with ND = 1x10^15 atoms/cm^3?
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What is the effect of adding acceptor impurity atoms to an intrinsic semiconductor?
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Study Notes
Semiconductor Materials
- A p-type material is created by adding trivalent impurity elements to a semiconductor material with four valence electrons.
- Trivalent materials have acceptor atoms, which create holes (missing electrons) in the material.
N-Type Extrinsic Semiconductor Materials
- Impurities used for n-type materials have five valence electrons (pentavalent) and are called donor atoms.
- The most commonly used impurities are antimony, arsenic, and phosphorous.
- Donor atoms introduce free electrons in the material, which are loosely bound to the parent atom and are relatively free to move.
- The majority carriers in an n-type material are electrons.
- Minority carriers in an n-type material are holes, which are created when electrons acquire sufficient energy to break from their covalent bond.
Extrinsic N-Type Silicon Crystal Structure
- The addition of a pentavalent material creates an additional fifth electron, which is unassociated with the covalent bond.
- The fifth electron is relatively free to move within the material and requires less energy to enter the conduction band.
P-Type Extrinsic Semiconductor Material
- Impurities used for p-type materials have three valence electrons (trivalent).
- The most frequently used impurities are Boron, Gallium, and Indium.
- Acceptor atoms create holes (absence of electrons) in the material.
Carrier Concentration
- For p-type material, the concentration of holes (majority carrier) is pp ≈ NA = 1x10^16 holes/cm^3.
- The concentration of electrons (minority carrier) is np ≈ 22,500 electrons/cm^3.
- For n-type material, the concentration of electrons (majority carrier) is nn ≈ ND = 1x10^15 electrons/cm^3.
- The concentration of holes (minority carrier) is pn ≈ 225,000 holes/cm^3.
Law of Electrical Neutrality
- The doping process determines the concentration of free electrons and holes in an extrinsic semiconductor.
- The addition of donor and/or acceptor atoms creates ions due to the gain or loss of electrons.
- Acceptor atoms become negatively charged, and donor atoms become positively charged.
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Description
Learn about the creation of p-type materials by introducing trivalent impurities to semiconductor materials, and understand the difference between p-type and n-type materials in terms of covalent bonds and electron carriers.
