Confusion about ionised atom, free electron, conduction band, donor energy level and acceptor energy level

  • #1
cemtu
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Homework Statement:: Ionised atom, free electron, conduction band, donor energy level and acceptor energy level
Relevant Equations:: None

I have some confusion about the concept of some electronic bands and energy levels.

Beyond valance band, in a solid crystal lattice,

For an atom, can having at least one electron in the conduction band mean that the atom has been ionised?

Can having an electron in the donor energy level or acceptor energy level mean that the atom has been ionised?

Is free electron same as an electron in the conduction band or an electron in the acceptor or donor band?

Is an atom having a free electron an ionised atom?

I am super-super-confused...
 
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Answers and Replies

  • #2
bob012345
Gold Member
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747
Homework Statement:: Ionised atom, free electron, conduction band, donor energy level and acceptor energy level
Relevant Equations:: None

I have some confusion about the concept of some electronic bands and energy levels.

Beyond valance band, in a solid crystal lattice,

For an atom, can having at least one electron in the conduction band mean that the atom has been ionised?

Can having an electron in the donor energy level or acceptor energy level mean that the atom has been ionised?

Is free electron same as an electron in the conduction band or an electron in the acceptor or donor band?

Is an atom having a free electron an ionised atom?

I am super-super-confused...
I have some confusion about the concept of some electronic bands and energy levels.

You are not the only one.

Beyond valance band, in a solid crystal lattice,

?

For an atom, can having at least one electron in the conduction band mean that the atom has been ionised?

Yes according to the Wiki articles referenced below but most of my semiconductor books do not use the word ionised but rather charged for the Donors and Acceptors.

.https://en.wikipedia.org/wiki/Ionization
https://en.wikipedia.org/wiki/Donor_(semiconductors)
https://en.wikipedia.org/wiki/Acceptor_(semiconductors)

Can having an electron in the donor energy level or acceptor energy level mean that the atom has been ionised?
Same answer but the electron is not in the acceptor level, the hole is.

Is free electron same as an electron in the conduction band or an electron in the acceptor or donor band?

A free electron is in the conduction band. Acceptor and donor are not energy bands but the type of dopant used to make P-type or N-type semiconductors respectively.


Is an atom having a free electron an ionised atom?

Removing an electron from an atom makes the atom ionised if that's what you mean..

I am super-super-confused...

I've been there.
 
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  • #3
hutchphd
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Homework Statement:: Ionised atom, free electron, conduction band, donor energy level and acceptor energy level
Relevant Equations:: None

I am super-super-confused...
I will not answer each of your questions now but point to the major source of your confusion.
The band structure in a crystalline solid refers to electronic states of the entire crystal. These maintain some of the form of atomic orbitals from which they are created but electrons in a solid do not belong to individual atoms. This is particularly true of the outer (highrer energy) bands. An electron in an insulator can be promoted to the conduction band from the valence band, but this does not mean any particular lattice atom has been ionized. Energy goes in and an electron is bopped to the excited state of the crystal.
 
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