Spectrum of emission in photoluminescence

[BelNaz]

hi,
i did an experiment of photoluminescence in the lab and i was wondering about the spectrum of emission.
why we get emission of photons with energies below the energy gap of the semiconductor?

thanks

 

[Vagn]

hi,
i did an experiment of photoluminescence in the lab and i was wondering about the spectrum of emission.
why we get emission of photons with energies below the energy gap of the semiconductor?

thanks

You will usually have defect states in your material, particularly for polycrystalline samples, the random distribution of defects will lead to band tailing, which can be observed in PL.

 

[BelNaz]

Thank You!