Why does recombination release light? It's one thing to say, 'and when the electron drops down it releases light', but it would be another level to explain how an electron dropping down creates an EM field- or something like that.
Dear Suraj,
This question is asked before in the forum given in the RG link:
https://www.researchgate.net/post/Generation_recombination_of_electron_hole_pairs_in_semiconductors
and i gave the following answer:
Your question concerns the nature of electrons and photons and their interactions. This topic has been treated intensively in the basic particle physics.
As far as i know the electron is a very tiny particle has a rest mass me and carries an electric charge q. When it moves, it moves like a wave. So, it is not a wave but moves like a wave. This wave motion is described by the laws of the quantum mechanics based on the Schroedinger equation.
In solving Schroedinger equation for the electron motion one considers that the electron has a mass and charge which are concentrated in a point.
When it is moving in the atom, it can be considered as affecting very tiny electric currents. The atomic magnetic moments are the consequences of the electron orbital currents and electron spin currents.
Therefore, based on the classical electromagnetic theory where an electromagnetic radiation will be emitted when time varying electric current exists.
I assumed that when the electron is falling from an orbit with higher energy to an orbital with lower energy it can be modeled by an impulse current. giving a flash of light which is a photon. This is just a model to bring plausibility explanation of the photo emission process.
Best wishes
Dear Suraj,
This question is asked before in the forum given in the RG link:
https://www.researchgate.net/post/Generation_recombination_of_electron_hole_pairs_in_semiconductors
and i gave the following answer:
Your question concerns the nature of electrons and photons and their interactions. This topic has been treated intensively in the basic particle physics.
As far as i know the electron is a very tiny particle has a rest mass me and carries an electric charge q. When it moves, it moves like a wave. So, it is not a wave but moves like a wave. This wave motion is described by the laws of the quantum mechanics based on the Schroedinger equation.
In solving Schroedinger equation for the electron motion one considers that the electron has a mass and charge which are concentrated in a point.
When it is moving in the atom, it can be considered as affecting very tiny electric currents. The atomic magnetic moments are the consequences of the electron orbital currents and electron spin currents.
Therefore, based on the classical electromagnetic theory where an electromagnetic radiation will be emitted when time varying electric current exists.
I assumed that when the electron is falling from an orbit with higher energy to an orbital with lower energy it can be modeled by an impulse current. giving a flash of light which is a photon. This is just a model to bring plausibility explanation of the photo emission process.
Best wishes
In the simplest case of a Si based diode, the term "recombination" means that a free electron encounters a hole, that is a localised uncomplete orbital of a dopant atom, and fill it by completing the orbital. In doing so, it assume the final bound state energy level and release the extra-energy (initial free electron energy minus final local binding energy) via emission of a photon.
Here's a quasi-quantum mechanical way to think of emission or absorption of a photon that purists will not like, but might be helpful en route to finding a deeper understanding for your very good question. Imagine a system that has a sharp resonance. And imagine a harmonic disturbance tuned to the resonant frequency. In this case, the resonant system is an atom and the disturbance is the oscillatory EM field of a passing photon. The photon field (and here, we're swapping between QM and EM pictures without apology) tickles the resonance of the atom and the photon energy is taken up in by the atomic system, which now is more energetic than before exposed to the field. Full disclosure: this picture works for a sound wave and a guitar string tuned to the sound wave, which is why we're using it for a harmonic EM disturbance and an atom, but there are details missing that will make the purists that I mentioned a bit unhappy. Now, imagine the energy held within the atomic system. For release of this energy, either spontaneously which has some probability of happening, or through a process stimulated by the passage of another resonant photon whose EM field shakes the atom, the atomic system has to oscillate in some sense at its resonant frequency. Imagine an atomic configuration characteristic of the high energy state and another lower energy configuration and imagine the atom shaking back and forth between these two configurations at its resonant frequency, which happens to correspond to the difference in energy between the states. The act of oscillation between configurations radiates energy out of the atomic system back into space in the form of an EM field which is the emitted photon. If the photon escapes from the atom on its own, we call it spontaneous emission. If another resonant photon helps the jailbreak, we call it stimulated emission. To preempt all those who understand the sins of this explanation that mashes up QM, E&M and mechanics in an unholy way, I offer this: the question was asking about photon emission when an atom drops from a high to low energy state. The sterile wording of some textbooks, 'drops into a lower energy state and emits a photon,' is exactly what leaves Mr. Prasad with questions that demand an intuitive picture of what happens. QM sometimes defies our intuition. So, the picture described here is an attempt, albeit one that misses out some details, to picture an object with a resonance, an oscillatory field tuned to that resonance and the exchange of energy between object and field. I hope it helps a bit.
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