In case of photo luminescence the decay time decreases with increasing observation energy and the variation is exponential in nature for a fixed excitation energy (for Silicon nanostrecture, Porous Silicon). Why it is happening so?
Ref: PHYSICAL REVIEW B VOLUME 48, NUMBER 23,(1993).
Dear Ujjwal,
From the principle point of view, the luminescence decay depends on the recombination rate of the excess charges produced by input photo excitation. The time constant of the radiation decay process is the lifetime of excess carriers in the material.
If the lifetime is constant then the rate of decay will be constant irrespective of the excitation level. However this is not the case in many materials. The lifetime may decrease with the increase in the excess electron hole pairs and this may be the case which you report upon. So, if the decay rate decreases appreciably it may result in smaller total decay time.
In summary, the decay rate is controlled by the lifetime of excess electron hole pairs which may depend on the excess charge concentration level.
wish you success
I imagine that this is because of the intraband nonradiative decay to the lowest energy of the excited state.. but also, if I saw the publication I might be able to advise better.
Dear Ujjwal,
From the principle point of view, the luminescence decay depends on the recombination rate of the excess charges produced by input photo excitation. The time constant of the radiation decay process is the lifetime of excess carriers in the material.
If the lifetime is constant then the rate of decay will be constant irrespective of the excitation level. However this is not the case in many materials. The lifetime may decrease with the increase in the excess electron hole pairs and this may be the case which you report upon. So, if the decay rate decreases appreciably it may result in smaller total decay time.
In summary, the decay rate is controlled by the lifetime of excess electron hole pairs which may depend on the excess charge concentration level.
wish you success
The rate of decay from the higher energies of a band is a combination of intraband nonradiative decay and interband radiative decay and is therefore faster for the higher energy end of the emission. The intraband decay rate depends on the Boltzman distribution of occupancy of the excited state.
Dear Hugh J Byrne sir, can you send me some reference about Boltzman distribution of occupancy of the excited state.
Thanks
What is the relation between PL decay time and electron-hole recombination ?
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