Conduction and valence bands in semiconductors

Thus, the conduction band states are indeed s-type and the valence band states are p-type.In summary, the conduction band state is typically s-type and the corresponding valence band state is p-type for direct-gap semiconductors near the conduction band minimum. This is due to the spherical symmetry of the Bloch lattice-function for these states. However, this is not always true and is material dependent, as seen in the example of Cu where the 3d electrons participate in the conduction band. It is important to cite the specific material and location in k-space when considering the band states.
  • #1
Benevito
16
0
Why is the conduction band state s-type and the corresponding valence band state p-type?
 
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  • #2
This is not generally true. What material are you considering and where in k-space?
 
  • #3
Benevito said:
Why is the conduction band state s-type and the corresponding valence band state p-type?

You really should cite where you get such a thing.

As DrDu as pointed, this is not true always and it is material dependent. For example, Cu, a common metal, has the 3d electrons as its valence shell, and thus, the 3d electrons that participate in the conduction band, not the 4s electrons. This already negates the starting point of your question.

Zz.
 
  • #4
For example, here https://www3.nd.edu/~djena/kdotp.pdf [Broken] it is stated that "For direct-gap semiconductors, for states near the conduction-band minimum (k = 0), the Bloch lattice-function possesses the same symmetry properties as a |S> state . In other words, it has spherical symmetry. The states at the valence band maxima , on the other hand, have the symmetry of p-orbitals"
 
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1. What is the difference between conduction and valence bands in semiconductors?

The conduction band is the energy level in a semiconductor where electrons are free to move and conduct electricity. The valence band is the energy level where electrons are tightly bound to atoms and cannot conduct electricity. The energy gap between these bands determines the conductivity of a semiconductor.

2. How do impurities affect the conduction and valence bands in semiconductors?

Impurities, also known as dopants, can introduce additional energy levels within the band gap of a semiconductor. These energy levels can either create new conduction or valence bands, making the semiconductor either more conductive or less conductive, depending on the type of dopant used.

3. What is the role of temperature in determining the position of the conduction and valence bands in semiconductors?

Temperature affects the energy of electrons in a semiconductor, causing them to move between the conduction and valence bands. As temperature increases, more electrons are able to jump from the valence band to the conduction band, increasing the conductivity of the semiconductor.

4. Can the position of the conduction and valence bands be altered in semiconductors?

Yes, the position of the conduction and valence bands can be altered through the process of doping. By introducing impurities into the semiconductor, the energy levels and band gap can be changed, affecting the conductivity and other properties of the material.

5. How do conduction and valence bands contribute to the operation of semiconductor devices?

In semiconductor devices, such as transistors, the control of electron flow between the conduction and valence bands is crucial. By manipulating the position of these bands through doping and applying electric fields, the behavior of the semiconductor can be controlled and used in various electronic applications.

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