Indirect Transition in indirect semicondutor material

In summary, the energy is generally given up as heat to latice rather than as an emitted photon in an indirect semiconductor material transition.
  • #1
itsbiprangshu
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In case of indirect transition in an indirect semiconductor material, momentum as well as energy changes. I got from the book "solid state electronics devices" by Streetmen & Banerjee that in such kind of transition "the energy is generally given up as heat to latice rather than as an emitted photon". Then my query is what is the basic difference between Heat to latice & photon emmission. Beacause as per my knowledge heat is infrared & infrared emmission is nothing but low energy photon emmission. Then how the heat & photon emission are different.
 
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  • #2
Well this is what I know. I hope I'm not too mistaken:
A photon provides very little momentum, as you can see easily from the de Broglie's relation. There is a huge change in momentum when an electron emits a phonon and drops from from the conduction to valence band (for an indirect bandgap semiconductor), whereas the momentum change due to photon emitted for a direct-bandgap semiconductor recombination is negligible.
 
  • #3
itsbiprangshu said:
In case of indirect transition in an indirect semiconductor material, momentum as well as energy changes. I got from the book "solid state electronics devices" by Streetmen & Banerjee that in such kind of transition "the energy is generally given up as heat to latice rather than as an emitted photon". Then my query is what is the basic difference between Heat to latice & photon emmission. Beacause as per my knowledge heat is infrared & infrared emmission is nothing but low energy photon emmission. Then how the heat & photon emission are different.

"Heat to the lattice" means that the energy stays within the material in the form of lattice vibrations (phonons). This is not an EM radiation such as IR. The lattice may later on radiate this as IR, but this is not a direct result of the transition, i.e. the IR has a wider spectrum than a direct transition.

Zz.
 

1. What is an indirect transition in indirect semiconductor material?

An indirect transition in indirect semiconductor material is a type of electronic transition in which the electron changes energy levels without changing its momentum. This occurs when the energy of the electron is not enough to overcome the bandgap of the semiconductor material, resulting in a longer transition time and a lower probability of occurrence compared to a direct transition.

2. How does an indirect transition differ from a direct transition?

An indirect transition differs from a direct transition in that it does not involve a change in momentum of the electron. In a direct transition, the electron changes energy levels and its momentum at the same time, resulting in a higher probability of occurrence and a shorter transition time.

3. What are the implications of an indirect transition in semiconductor materials?

The presence of indirect transitions in semiconductor materials can have significant implications for their optical and electronic properties. Indirect transitions result in a lower efficiency of light emission and absorption, as well as slower charge carrier recombination rates. This can affect the performance of devices such as solar cells and LEDs.

4. How can indirect transitions be manipulated in semiconductor materials?

Indirect transitions in semiconductor materials can be manipulated through the use of strain engineering or alloying. By applying strain to the material or introducing different elements into the material, the band structure can be modified to increase the probability of direct transitions and improve the material's optical and electronic properties.

5. Is there any ongoing research on indirect transitions in semiconductor materials?

Yes, there is ongoing research on indirect transitions in semiconductor materials, particularly in the development of new materials and techniques to manipulate and control indirect transitions. This research is important for improving the efficiency and performance of optoelectronic devices and for advancing our understanding of the fundamental properties of semiconductor materials.

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