Question

If why is can polaron exist in band gap while electron can't though they are both almost identical. Also, do the formation polaron exist as somewhat of a 'bridge' to narrow the gap between conduction band and valence band?

Options:
A) Due to the inherent mass difference between a polaron and an electron, allowing the former to exist within the band gap.
B) Electrons possess a higher effective mass within a crystal lattice, enabling the formation of polarons in the band gap.
C) Polarons form due to electron-phonon interactions, altering the charge distribution and allowing their existence in the band gap.
D) The formation of polarons primarily occurs due to the alignment of magnetic fields, creating a bridge between the conduction and valence bands.

Answer 1

c. Polarons can exist in the band gap due to electron-phonon interactions, which alter the charge distribution and enable their existence within the band gap. Electron-phonon interactions cause a distortion in the crystal lattice and the formation of localized electron-phonon states known as polarons.

Step-by-step explanation:

Polarons can exist within the band gap while electrons cannot due to electron-phonon interactions, which alter the charge distribution and enable the existence of polarons within the band gap (C). Polarons form when an electron interacts with lattice vibrations, or phonons, in a crystal lattice.

The interaction between the electron and phonons leads to a distortion of the crystal lattice and the formation of a localized electron-phonon state, known as a polaron. This distortion allows the polaron to exist within the band gap.