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Questions and Answers
What type of atoms are introduced into a semiconductor material to create a p-type material?
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 is the characteristic of an n-type material?
What happens to the covalent bond when a pentavalent material is added to a semiconductor?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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.
