Since using PLE carriers can be excited to the bottom of the conduction band, where they kinetic energy is zero it should be less probable to detect luminescence coming from carriers influenced by defects. Is that correct?
Dear Filip,
let us short discuss the difference between PL and PLE. A PL (photoluminescence) spectrum exhibits a whole emission spectrum what is generated at a certain excitation wavelength. This spectrum contains a superposition of different excitations, like band-band transitions, excitons and so on.
An excitation spectrumworks as follows: You put your sensor (receiver monochromator) on a special emission wavelength - lets say you want to observe an exciton. Then you select from your emission spectrum the exciton recombination energy. After this you scan the excitation wavelength and you get a very selective spectrum for your exciton. Therefore is clear:
The photo excitation spectrum is a high selective method to study a certain excited state.
With Regard
R. Mitdank
Ideally PLE should be similar to the absorption spectrum. If not interesting stuff start to appear starting from trap states phonon Effects thermalization rotations and so on .....
Dear Filip,
PL is more appropriate to detect defects in solid. Because, if you don’t know the defect energy (defect level emission) it is difficult to acquire corresponding excitation profile. Whereas, if you know the band gap of solid, any excitation energy larger than Eg can be useful to obtain overall emission profile of the solid. If radiative defect states are there in the sample, it can be obtained from corresponding PL spectra.
Best Regards,
SS
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