A short query on annihilation process

In summary, the process of annihilation in semiconductors involves the movement of electrons from the valence band to the conduction band, as long as they have enough energy. However, recombination can also occur, pulling the electrons back to the valence band. This process is normally in equilibrium in semiconductors, with generation and recombination occurring at similar rates. However, these processes are often ignored due to their slower time constants compared to transport times. For more information on this topic, refer to Pierret's book, Advanced Semiconductor Devices.
  • #1
NJunJie
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How does this annihilation process play in semiconductors?
Initially i thought that as long as the an electron gets enough energy to move into conduction band (in an energy diagram) - it will move and wander within the Conduction band. However, i have a slide notes about annihilation that talks about recombination.
How does this comes to play? - Does this means that although the electrons gets excited into Conduction Band - still there is some energy in the electron that will pull the electron back to Valence Band?
 
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  • #2
Normally, recombination and generation are in equlibrium in a semiconductor... For each electron that's recombined, another one would be thermally excited "ON AVERAGE"...

Normally the time constants for such processes are way slower than transport times so they are ignored most of the time.

For a comprehensive analysis, See Pierret - Advanced Semiconductor Devices.
 
  • #3


The annihilation process in semiconductors refers to the recombination of an excited electron and a hole (a positively charged vacancy in the valence band). This process plays a crucial role in the performance of semiconductor devices, as it determines the efficiency of electron-hole pair recombination and the resulting emission of light or heat.

In semiconductors, when an electron is excited into the conduction band, it leaves behind a hole in the valence band. This excited electron can then move freely within the conduction band, contributing to the electrical conductivity of the material. However, as you mentioned, there is still a chance for this excited electron to recombine with a hole in the valence band.

The recombination process can occur through different mechanisms, such as radiative recombination (emission of light) or non-radiative recombination (emission of heat). The probability of recombination depends on several factors, including the concentration of electrons and holes, the energy level of the excited electron, and the presence of defects or impurities in the material.

In short, the annihilation process in semiconductors refers to the recombination of an excited electron and a hole, which can limit the efficiency of electron mobility and affect the performance of semiconductor devices. As a scientist, it is important to understand and control this process in order to optimize the functionality of semiconductors in various applications.
 

What is an annihilation process?

An annihilation process is a type of particle collision that results in the total conversion of mass into energy. It is often associated with the annihilation of a particle and its antiparticle, producing two or more new particles.

What is the significance of annihilation processes in physics?

Annihilation processes play a crucial role in understanding the fundamental laws of physics, particularly in the study of particle physics. They help scientists understand the behavior and interactions of particles and their antiparticles, and provide valuable insights into the nature of matter and energy.

How are annihilation processes observed and studied?

Annihilation processes are typically observed and studied using high-energy particle accelerators, such as the Large Hadron Collider. These accelerators can generate collisions between particles at extremely high speeds, allowing scientists to study the resulting annihilation processes and their outcomes in detail.

Can annihilation processes occur in nature?

Yes, annihilation processes can occur in nature. For example, annihilation reactions between particles and antiparticles are thought to have occurred in the early universe during the Big Bang. Additionally, they can also occur in high-energy cosmic ray interactions in space.

Are there any practical applications of annihilation processes?

While annihilation processes are primarily studied for their role in understanding fundamental physics, they also have some practical applications. For instance, positron emission tomography (PET) scanners use the annihilation process of a positron with an electron to produce images of the body's internal organs and tissues.

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