Excitation = Exciton? - Physics Stack Exchange
2024年7月25日 · An exciton is a bound interaction between the electron and its hole. It has a lower energy than the lowest conduction band state, and it is often observable through photoluminescence (at a wavelength longer than what's needed to excite the electron-hole pair) as the pair recombines. Not every material demonstrates these exciton-specific properties.
solid state physics - Energy of exciton formation in …
2020年10月20日 · An exciton can form when a material absorbs a photon of higher energy than its bandgap I looked at absorption enhancing effects of excitons, and am aware of the Hydrogenic series for an exciton. It seems to me that the absorption of light energy below the bandgap is due to exciton formation.
What's the difference between an exciton and a geminate pair?
The electron in the electron-accepting material and the hole in the electron-donor material remain bound by electrostatic interaction, so they exist as a geminate pair. The binding energy of this pair is less as compared to the exciton in the homogeneous medium by the difference in electron affinities of the contacting materials.
How do experimentalists measure the exciton binding energy?
2022年6月1日 · The exciton binding energy in semiconductors is determined theoretically by the energetic difference between the fundamental gap and the optical gap or, in other words, as the energetic difference of the fundamental gap and the first exciton peak in an optical spectrum. My question is related to experiment.
How to understand exciton? - Physics Stack Exchange
2017年10月28日 · An exciton really is a electron coupled to a hole, just as you said. A electron gets excited to a higher band, leaving a hole in the lower band behind (a bit like a bubble on top of a liquid). You can disregard the other electrons (and holes) in this picture, as they are smeared out and just form the background.
Spin and wavefunction of Excitons - Physics Stack Exchange
2022年2月3日 · In problems where the exciton is tied to an optical excitation, we can compare its spin to that of the band before the excitation - knowing that the photon carries spin 1. In the naïve theory starting with non-interacting electrons and holes, this is then collapsed onto the optical selection rules for the heavy and the light holes or something ...
Why is the exciton binding energy slightly smaller than the band …
2016年12月7日 · An exciton is an interaction between what were originally a free electron and a free hole. Through the Coulomb force, these pair to generate a pseudo-hydrogen like complex. I might suggest looking at Jacques Pankove's excellent 'Optical Processes in Semiconductors', where excitons are introduced on page 12.
quantum mechanics - What are dark excitons and how to find …
2019年3月18日 · In order to create or anneal a dark exciton one needs to not only transfer energy to one of the constituents, (which mostly comes from the photon) but also transfer momentum to either the electron or the hole (which comes from either phonon absorption or phonon emission). Dark excitons can therefore actually be thought of as three-particle ...
optics - Why is an exciton only observed when we excite to the ...
$\begingroup$ I should know this but I don't: I do not understand, in this case, the difference between a bimolecular and a monomolecular system and why the latter does not form an exciton. Maybe what I misunderstood is that an electron cannot in fact be excited from the valence band of the host to an energy level of the RE dopant.
quantum mechanics - exciton binding energy and orbital binding …
2016年3月22日 · However, exciton is somewhat more complicated, it is, by definition, collective excitations of the electron-hole plasma. The hydrogen model allows you to get right position of exciton peaks only at 0 K temperature, but it does not give a clue why these peaks change with temperature and carrier concentration.