Table of Contents
How is exciton produced?
1 Introduction. Exciton polaritons are quasiparticles formed by strong coupling between cavity photons and semiconductor excitons. The photon component makes their effective mass very small, and therefore enables quantum degeneracy at high temperature.
What is exciton recombination?
As a result of absorption of photons of energy equal or greater than the band gap energy of the semiconductor, the excitons (electrons and holes) are generated in the conduction and valence band, respectively. This is called exciton recombination. The same phenomenon is also present in an organic semiconductor.
What is called exciton?
An exciton is a bound state of an electron and an electron hole which are attracted to each other by the electrostatic Coulomb force. • Attraction between the electron and the hole causes their motion to be correlated and the resultant electron-hole pair is known as an exciton.
What are exciton give its types?
This is termed as exciton. In organic materials two models are used: the band or wave model (low temperature, high crystalline order) and the hopping model (higher temperature, low crystalline order or amorphous state). Energy transfer in the hopping limit is identical with energy migration.
What is self trapped exciton?
Self-trapped excitons (STEs), occurring in a material with soft lattice and strong electron–phonon coupling, emit photons with broad spectrum and large Stokes shift. Recently, series halide perovskites with efficient STE emission have been reported and showed promise for solid-state lighting.
What is a free exciton?
A free exciton is a bound electron-hole pair that has a binding energy of a few meV. Generation of electron-hole pairs in a semiconductor can be achieved by illuminating a semiconductor sample with light with photon energies larger than the energy gap of the semiconducto.
What is exciton Rydberg energy?
Confined to a quantum well, Rydberg excitons gain energy, so they experience an energy blue-shift. Within the weak confinement regime, this energy shift accounts for a few and a few tens of μeV for the lowest and third excited quantum state index, respectively.
What is self trap?
Self-trapping occurs when the self-interaction energy between the Bosons is larger than a critical value called . It was first described in 1997.
What does self trapped mean?
When an electron or a hole is inserted into an insulator, it often gets self-trapped” by deforming the local lattice structure. This permits a localized bound state to form with a lower energy than simple insertion of an electron or hole into the conduction or valence band.
What is positive hole?
A positive hole in a semiconductor is a vacancy which is created at the site of a covalent bond when an electron leaves a covalent bond.
What is the charge of exciton?
The exciton is regarded as an elementary excitation of condensed matter that can transport energy without transporting net electric charge. An exciton can form when a material absorbs a photon of higher energy than its bandgap. This excites an electron from the valence band into the conduction band.
What is an exciton in physics?
Exciton, the combination of an electron and a positive hole (an empty electron state in a valence band), which is free to move through a nonmetallic crystal as a unit. If the energy is transferred to a neighbouring electron, a new exciton is produced as this electron is forced away from its atom.